Labradoodle - recently destructive when home alone

Question
We've had our labradoodle since she was 4 months old (she's now a year and
8 months).  We have no other dogs.  Four the last month or so, she's been
reaching up on the counters and chewing things up when we leave her at
home by herself.  My wife is at home during the day and I take the dog for
walks/play frisbee with her at least once a day for at least 30 minutes, careful
to not let her demonstrate pack leader behavior.  
Three weeks ago, she chewed up a blackberry for the first time (the
blackberry has been around for over a year) and this evening she peed on a
rug even though she is reliably house trained.  We are not gone longer than 4
to 5 hours at any stretch.
We have recently had a our first child (3 months) and suspect that we may be
seeing behavioral issues stemming from the new baby.  The dog has never
been allowed to sleep in our bedroom or the guest bedroom (now the baby's
room).  We are at a loss to understand the 'surprises' we get when we come
home since this was not an issue before.
We have attended off-leash training with our dog and we are careful not to
'humanize' her (i.e. no human food, no 'conversation' with her, not allowed up
on couches or beds, etc.).  She listens well and is not destructive/does not
pee when we're home.  
Not sure if this behavior is related to the baby, if the dog is challenging the
pack order, or something else.  Any help you can provide would be greatly
appreciated!

Answer
This is most likely a reaction to the enormous change in environment, vis a vis, the baby.  However, any extreme change in behavior must be checked out with the veterinarian. One never knows when any dog might develop an orthopedic problem, a parasite (intestinal, or mosquito related), etc., so to be safe that's your first stop.

Regarding no "conversation" with her, I'm unsure what this means.  While it's good not to 'humanize' a dog member of your family, the dog still requires one to one attention, not just exercise.  Positive reinforcement training is fun for both dog and human and you should be spending some time each day (you and your wife) teaching her one behavior at a time that you can require of her and for which she can be lavishly rewarded.  Your dog may feel insecure regarding her place in your family (pack, although I hate using that term).  Some brief (15 minutes twice a day) positive reinforcement training will be good for all of you and help her to feel more secure about her place.  Insofar as destructive behaviors are concerned (and unwanted elimination), this all may very well be the result of her insecurity.  Marking behavior can also be the dog leaving scent not just to secure her "place" but also to warn off other dogs (because of the infant toward whom she might be feeling a protective instinct.)  

First: do not leave articles available to her when she is left alone.  There is nothing wrong with confining her to one area, such as the kitchen; leaving a dog alone in charge (as the dog perceives it) of your entire living space is a huge responsibility.  She will be happier if confined with a soft bed and some special toys (marrow bone, kong with a teaspoon of fat free peanut butter).  You can also set the dog up to "punish" her countertop navigation by using a sound punisher (such as several empty soda cans with 8 pennies a piece, pinched in the middle to prevent the pennies from coming out; place them on the counter on a large paper towel section with a set up "food", such as a small piece of sandwich; when the dog pulls down the paper towel and sandwich, the cans come with it, creating a startle effect.)  I don't much like using this approach without being able to ascertain temperament in the dog, since it's an unfair approach toward a dog that is basically bidable and soft tempered.

Regarding the blackberry, this most likely has your scent and you may very well have given her a great deal of attention for obtaining it.  "Stealing" an "important" object is an attention getting behavior which almost always backfires on the dog, because the humans involved are anxious, chase the dog, are often angry, and the dog then becomes frightened and is not in any way cognizant of its own behavior having precipitated the event.  If she is contained when you are not at home, and if objects that are important to you are not available to her, she is unlikely to repeat these behaviors.  The Labradoodle is an excellent companion dog and you obviously spent a great deal of time attempting to make her a good companion.  This is a small bump in the road; she is a very young dog; she requires some more quality time with you and your wife and a bit more structure, just as you will provide for your infant when s/he becomes a toddler.  Any further questions, don't hesitate to repost.