growling

Question
ok, we have the most unusual dog I have ever seen.  I will give you a short history in order to ask my question.  She is 15 month old black lab and spayed.  she came from a breeder and they decided to stop breeding and wanted to find a good home for her.  she is the most incredibly calm dog I have ever seen (more calm than an 8 year lab that we used to have).  she wasn't raised with children but had grandkids over occasionally so she had exposure.  she is very obedient.  she seems almost lazy, she just lays around, but follows us all over the house.  her first week here with us she was very nervous.  she wouldn't eat and was afraid of every noise and everything new to her (but she is better now, but still gets afraid of new noises).  anyway besides all of that, the question is that my 7 year old son who is more playful with her down on the floor and the dog licks his face excetera, but the other day the dog growled at him when he had his face on her tummy playing.  so is this an indication of a bad thing?  will the dog get worse and turn on him and/or actually bit him?  we do not want to risk anything. yes a young boy is a little more "hyper" but he is quite gentle and we have explained to him about being easy with the dog, so he is not hurtful or aggressive with the dog, but just more right there on the ground with her and mingling around with her.  I know labs are supposed to be great with kids, so a growl was quite unexpected and I don't know what that really meant.  my son was here first so I want to be sure that this is a good match for our family.  thank you for your expertise and any thoughts on this. sharra

Answer
Labs and children usually do well together.  Due to her background, you may have to do soume extra work.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm  That site has some additional material on dogs and children you need to read.