*NOTE* If you're not comfortable reading about/discussing sexual behavior in kittehs, please stop reading.
So I have a twelve year-old male cat who was neutered at a very young age, and he's never exhibited any signs of a non-fixed cat, even when he was friends with several female cats at our old house. Suddenly in the last few weeks he started kneading more than usual (just the normal, kitten-type kneading) but he's always done that. And then, one day, it changed to something else. He was, for lack of a better/more sophisticated term, humping my foot. He's been doing this kind of thing more and more and it's kind of freaking me out.
Does anyone else have this problem or have any idea what to do in this situation? I'm a little worried because I've heard that it could be a sign of depression or something, but he seems normal and happy otherwise, he still plays like he's a young kitten, and he still eats, drinks, and goes outside. Any help/advice is appreciated, thanks!