Hmm. I've heard of a mega event like that (plus the normal Fundamentalists event, which only hits the evil players), but what I'm thinking of is a non-random rebellion based off of low approval, as the descriptions for advanced governments and the manual hint is possible.
The main reason this has come up is that in my current game, the Krynn have the angriest planets I've ever seen in 40-something games. Except where they've built morale structures, every world is at 35% approval, or worse on high-pop planets. Since the Krynn and I are probably headed for war, it would be nice to know if there's any chance of a rebellion coming up and distracting them. (If not, at least Information Warfare should pay off big).