My 1 1/2 yr old GSD (Diesel) has growled at my son before, but only when he was in his cage and only did it a couple of times. The other day we had just came back from a walk. Diesel was laying accross my lap and i was petting him, my son walked over and was rubbing him on his head and Diesel was letting him. My son stepped back away and said "Diesel's a good doggy" then Diesel growled at him and acted like he wanted to lunge at him but luckily i still had him on the leash and he couldn't pull away from me. I'm unsure on what to do now. My wife wants me to get rid of him and I think maybe I should. Any suggestions would be appreciated. Thanks.