Phil, it is very likely your 'dead' wasp could have been a hibernating queen.
I have been stung twice on the back of my left thigh, both times in January, once from one in one of the 'cells' of a foam rubber tractor cushion and last January down the side of an easy chair in the lounge. As a result I tend to discourage them coming indoors in the Autumn!!
Happy New Year to all,
David Lucas