I don't see what the big deal is about? My little guy got neutered when he was 3 months old (he's now 9 months) and he humps his teddy bear all the time! I think it's completely normal. I just don't have the heart to take her away from him.
I would have a problem if he started humping people's legs, but he has never tried that. Anyways just letting some of you know that his didn't stop after he was neutered.