My APBT W.S. is about 4 months. LAtely once in a while when I play tug-o-war with him, He'll start humping the air while hes tugging. I say "aye" in a frim voice and make him sit and he will stop. I was wondering if this is a sign of him showing dominace or is he getting aroused(lol) or something because he is hitting puberty? ANy input and feedback would be greatly appreciated.