I have a 3 month old choc. lab pup and I have basically the same problem. However, we have started obedience training and the biting seems to be much better since the start of training. All pups explore the world with their mouths and I believe, especially labs. I think this is a small problem that he will grow out of. My training instructor tells and the books I have read, tell me to redirect the biting of humans to one of his chew toys. This works well. I agree with the other responder that your pup is teething and will grow beyond this behaviour. Please don't give up your pup for a behaviour that is natural to him. All pups must learn to inhibit their bite. This is a normal part of life. He will eventually get the message that he is hurting you with his bite and will learn to bite with control. I believe dogs will always "play bite" their entire lives as a part of healthy play. Retrievers must learn to have a "soft mouth" in order to become a good retriever and I believe your dog will.