Hey John -
I know what the problem was. We are doing a big update today (being a weekend day), upgrading everyone's account to get ready for next week's Method Warehouse release (oops....did I just leak that info?) :).
It should have been invisible to everyone, but you may have logged in just when the upgrade was going through your account, bad timing, that's all. My guess is that screen was the most recently created screen you customized?
I also bet that next time you logged in it fixed itself automatically.
So that is the reason behind it. Totally on our end, nothing you did. I apologize for the inconvenience, and I'll look into ways to prevent this from happening in the future.
Paul