So would you get angry if a sabre-toothed tiger charged at you when you weren't expecting it? Do you get angry when a clear day gives way to rain? Do you get angry when a short story has a twist ending?

For me at least, the answers are no, yes, and no respectively. We can further refine the prior hypothesis by stipulating that the bad feelings arise from expectations not being fulfilled in an unpleasurable way, which would stop it from generating the third situation as an example. As for the first, perhaps one might experience anger if it were not being overridden by the more pressing reaction of fear. Or perhaps the hypothesis is off base, but it seems to generate some correct predictions of anger which the hypothesis that anger only arises from frustrated expectations about social rules fails to generate.