Running: Kind of TMI

Okay so I'm kinda weirded out. When I run for extended periods of time like at the gym or something, my vaginal muscles like loosen up and it feels like I'm about to pee? I know that's not my vaginal muscles but the more I think about it it's almost an orgasm feeling?? I'm so confused and I hate it when it happens. Does this happen to anybody else? Or am I just weird? Any tips to get it to stop?