Dexter is 5.5 months old and was neutered at 4 months. He used to hump me all the time and then stopped. Last week he started it with my husband (maybe 1x a night). I think we'll try the suggestions on that website. I really do think he's playing. He seems to do it when he's in need of a nap as well so we have put him into his crate when he starts doing it.