Facebook notification settings reset: implications

Today I received an email which may or may not have been from Facebook. It simply read:

Unfortunately, the settings that control which email notifications get sent to you were lost. We're sorry for the inconvenience. To reset your email notification settings, go to: http://www.facebook.com/editaccount.php?notifications
Thanks, The Facebook Team

I'm always on my guard when it comes to things like this, and feared it was a phishing scam where someone was trying to steal my details. After all, how could Facebook lose such important settings? Email notifications allow you to let Facebook send you alerts when something happens, so you don't have to constantly log into the site. But such alerts can be annoying -- you can get alerts for every tag, event or group invitation. So I've pretty much turned all of these off. Surely Facebook couldn't lose these settings?

Well, when I logged in to Facebook I got a similar message:


Logging into the notifications page, sure enough, most of my alerts had been reset so that I had to change THIRTY-TWO...(32) email alerts to "off".

Email alerts don't pose privacy problems as such; just annoying alerts (although if you use Facebook at work, such excessive alerts could be picked up by your IT/HR department so they can detect your activity). But the technical glitch does make you think of more serious scenarios, namely the loss of privacy settings. Does Facebook have these backed up? What if all privacy settings were suddenly reset and your profile was exposed to more people than you'd intended -- even though you, as a responsible and privacy-conscious Facebook user, had painstakingly set up your Facebook privacy profile?

I'm interested in hearing what Facebook has to say about it. In the meantime, I'm doing a screen shot or noting down my current privacy settings and double-checking a few things.