hummm...
You also have to take into account for your DS that his Intellect far outstips his proccessing speed - so he has lots and lots of experiences where he feels he 'should' be able to do stuff that he hasn't been able to.
My guess is that his hissy fit is because he was reminded of his many experiences of this frustration. See if an hour or two after the hissy he seemed to 'have more attention' for the kinds of tasks that are usually difficult for him. If so, then I would say the hissy fit was a 'cleaning tornado' where a person cleans up old hurts to 'clear the deck.'
