Bug with viewing mutual friends?

Hi there,

Well, situation is that when I search a person whom I'm not friends with, it says that we have two mutual friends (whilst on the search bar, right below his name), but when I check the friendship with that person using the "http://www.facebook.com/[User ID or Username #1]?and=[User ID or Username #2]" it says we have no friends in common. How is that possible? What info should I believe?

Thanks in advance,