Your dog is probably learning to interact and nipping and biting is one form of interacting. My dog also did this but it has died down. I used Carrie's suggestion and would give him his ball, it was kinda like a dummy for babies. Another suggestion is to hold the dogs tongue down with you thumb ONLY for a few seconds each time he bites. Of course Carrie's suggestion is more dog friendly, but this suggestion can be tried down the track.