I got notified just now (red banner at the top of the page) that I had gained the privilege to vote down and 1 other privilege. Trouble is, vote down requires 125 rep and I passed that point back in October! I don't think I have gained any new privileges since I passed 3000 rep, back in mid-December or so. Maybe this is just a random hiccup. Do others see this happening?
There were some significant changes to the privilege system, so you may have gotten re-notified this once.
I just got a badge for flagging a post ("Citizen Patrol"?), and I didn't do any flagging recently, so there must have been a database glitch that cause it for both of us.