Just a note that this was an unfun bug, but it was just a bug. Our backend authentication system wasn't responding properly, and, as these things happen, it started in the middle of the night. But we did push an engineer out of bed who could diagnose it and get it fixed, and we're looking at a more robust fix to keep it from happening again.
And while I'm here being open (grin), we did find that we're not happy with our escalation tree for such things when most people are out of the office, and we're putting together a better plan.
Christopher