Isaac likes to do what I call "Fake suckling". He doesn't actually suckle, but he kneads, rubs his face, and drools all on my arm. Lately I've noticed that his back end has started doing some actions that I do not appreciate. He is 4 years old and neutered. I get the suckling behavior, but why is he also, well for lack of a better word humping at the same time? It's very strange, and I would say started in the last six months. He had his regular check up a month ago, all looks fine health wise.