I've been experiencing a great deal of anger/agitation lately myself, so I can relate. It doesn't take much at all to set me off. As a matter of fact, at the bank the other day, the only thing that kept me from really going right off the deep end was fear of getting arrested or tossed in a rubber room.

I don't know what I can suggest for when it happens. When I get like that, sometimes I don't want to calm down, I almost revel in it. Not good, I know, but fortunately it tends not to last long like that, as you described. But if it helps, you're not alone in feeling that way.