Annoying Critical Update Available?

I installed Firefox 0.9.1 and since I've had a small yellow-on-red exclamation mark on the status bar, right hand corner. The tooltip reads "Critical Update(s) Available": Firefox 0.9.1. But I already have it! I guess it's a bug in the system. If you have this problem too, you can change one variable in your user.js or about:config:

user_pref("update.app.updatesAvailable", false");

and restart Firefox. Voilà!