I really think this is very, VERY common and doesn't necessarily mean there's a problem there. How many men have you seen leaving the bathroom with dribble stains on their pants? Not that I actually look for that kind of thing, but many times it's very obvious.
I think it has something to do with urine that's still left in the urethra and just doesn't get shaken out when they are done.
Who knows, men may have a different take on it though.