The weirdest thing happened to me today. I was playing A Strnager's Call on Destiny, and after I killed all the Vex, and the cutscene started playing. I watched, and out of nowhere--literally in the middle of the cutscene, I unlocked an achievement...for Saints Row IV.

It gets weirder. Apparently, I unlocked the Don't Panic achievement--something linked to an action I performed...a full month ago.

What's all that about??

Someone in Redmond rebooted a server.

I guess for some reason that achievement unlocking caused a refresh/re-examination/whatever-it's-called of the master list of which achievements you'd gotten. Exactly why it happened at that moment, I have no clue, but it seems to happen now and then. It might be that the check is programmed to occur every X number of unlocks, or something like that.