Why did I get an email saying I've asked a question on GameDevelopment.SE?

I just got an e-mail 3 hours ago from do-not-reply@stackexchange.com:

I'm pretty sure I have never asked a question here, or even known about this specific SE site's existence. Is this a bug, a january fools prank by SE, a phishing trick (can't be, do-not-reply at stackexchange is SE's official email), or has someone been using my acckount?

I've gotten the same e-mail about Sharepoint.SE, Unix.SE, Skeptics.SE, Japaneese.SE, HomeImprovement.SE, SciFi.SE, Personal Finance Money.SE Database Admins.SE and TeX.SE. I have previously posted on TeX.SE, but not anytime recently.

Thanks.