I always knew that friendships came and went. We have friends- maybe best friends- for certain times of our lives; they're there and then they're not, and you don't really mind because you're the same thing to them- someone for some time, and then no one at all. We have the 'kindy' friends, the primary besties, the high school bunch, and then the Uni acquaintances.
Now I'm not saying none of these people last, but it's rare, because when your sifting your life from one stage to the other, not much falls through. But there's always the exception, the odd ones that slip by and weave their way back into your life. In my case, through an out of the blue phone call and unexpected invitation.