I've discovered that when you disconnect the Volt from a Charger while it's locked the alarm will go off a few seconds later. I suppose this is to prevent someone from removing your volt from a charger without your knowledge or permission. While I appreciate the intent, I'd rather not wake up some of my neighbors if/when I forget to unlock the Volt before I disconnect it.
It would be nice if it gave two low warning honks, similar to the "Happy Honk" you get when you plug it in. So that you can unlock the car before the alarm goes off.