Were you somewhere that may be using caching between you and your webserver? I've had that before trying to use CPanel from a client site where stale pages were cached by the internet provider. It gets very frustrating. When I checked from another internet connection it was working properly again.

There are no external dependencies in the code so if it stops working there would probably be other stuff on your site that's stopped working as well.

Glad to hear it's back though...
-M