Crazy?

Has it ever happened to you? You try calling someone.. there's nothing major to talk... You reach their voicemail. You don't leave a message. Yet you keep trying them every few minutes even though somewhere in your head you are certain you'll reach the message. It happens to me enough for me to question it. What's that urge? Why do we do it? Is it just the curiosity or is it something more? After sometime, if I can't reach the person my frustration with them increases for no real fault of theirs. I guess somethings are just what you're born with.