Lab puppy problems with older dog

Question
Our new lab puppy was just purchased from a reputable pet shop at 3 months old. We have a 2-year old mini-schnauser (actually almost large enough to be a standard) who is a wonderful and sweet dog.

When we introduced them the Lab began playing immediately and tries to bite the older dog, playfully I assume although the older dog clearly wants none of it, tries a submissive posture, and when that doesn't work there is growling. We only let it get that far a few times.

We correct her immediately whenever she attempts to bite, which has been often, a simple "no biting" and introduction of a chew-toy is having the desired effect, but she always goes for our other dog mouth-open.

How should we proceed? Is this normal? Should we keep them separated until the puppy is older (that doesn't seem like a good idea). Is it just a matter of correction?

The Older dog socializes well, we have taken him to a Dog Park many times and he is clearly a submissive follower-type and just not aggressive at all.

Some guidance would be appreciated, thanks.

-Nippy in San Diego

Answer
I would expect that more from an older dog.  Perhaps the puppy is just too big. At 3 months it is past the puppy breath and the other dog may not realize it is a puppy.  The puppy may not have learned the right play signals if it spent too much time by itself in a cage.  

It may just need to learn not to bite the older dog just as you are teaching it not to bite you.  We have our third puppy since 12 year old Aster the grouch came to live with us.  She wants nothing to do with their sharp little teeth.