Yes, but I know why it happened to me, twice.
Oh, and your online stats aren't saved on your PS3, they're saved on Activision or Infinity Ward servers.
First time: My PS3 got YLoD and I had to get a new one.
Second time: I was deleting an offline profile (Me and my bro play sometimes) and accidentally deleted my save game, which is Spec Ops and Campaign, I had some of the campaign levels done on the hardest difficulty, which I forgot the name of right now, but it really sucked...
Sir Alex, the Ruby Knight of Everlasting Life