Is it normal that every time i visit my neighbor's house her dog gets 'excited' ?

My neighbor and I are best friends so we hang out all the time. Last year she got a Pit Bull puppy. He is so friendly and he gets along great with everyone. The only issue is that every time I'm around him he gets 'excited'. When he was a puppy it wasn't a problem, although he would stick his nose in my groin. When he was about three months old he started mount me. At six months he started doing this all the time. He's a good dog and has never tried to hurt me. What should I do?