Sometimes I get the urge to reconnect with people who've been out of my life. I always have at least one person in mind but I usually don't do anything until the mood strikes, then I typically seek out a few people at once. The mood sometimes includes reaching out to newer friends, people I don't know that well yet. It might seem like the mood is just a general "extroverted" phase, but I don't think so. For instance it seldom includes any extra desire to make entirely new friends.
I don't think it's about specific people. There's always a person or three atop my list and I do contact them first, but I'm not sure they cause the mood. They definitely don't hurt it, though. It might seem like a response to uncertainty or feeling unconnected, reaching out to see who's there. I don't think that's right either, since it seems to happen at high times, not low ones. So I guess I'm just not that sure what causes it or why it comes in waves. It could be the full moon, which would explain why missing people seem more likely to pop up around that time. ;)
What about you? What inspires you to seek out people you miss? How does it work for you? Do you do it in waves, right when you think of it, or how?