Over the years it happened to me a few times.
Every times it happened, I loged on to see the "someone to add you" message. I accepted, but the person was offline. Days later when I finally get to meet the person, none of us know who the other is.
Is there something more annoying than granting someone permission to add you to their friend list, just to have them ask you who you are and why you are on their friend list?