Help! I'm Trapped in the Elevator!

Today at work, I went down to the smoke hole with some fellow co-workers (I don't smoke). When we went to board the third floor elevator, we noticed it wasn't quite acting right, but it's always had a quirky personality. Not thinking too much of it, we got on, pushed the button, and the doors shut behind us. But then nothing happened. The elevator refused to budge. A quick glance around the compartment, followed by a nervous laugh. One of us decides to try to pry the doors open with our fingers. No luck. Uh, this sucks. We pushed the call button. After a couple of rings, someone actually answered our call. "Dominoes pizza!" Just kidding. I have no idea who it was. After talking to the guy for about 10 seconds, one half of the door opens. Deciding not to tempt fate, we step back out into the hallway and decide to take the stairs. All in all, I was only trapped for about 20 seconds, but that was long enough.