A wasp mystery

Early Tuesday morning, I had to work on a balky contactor in a shack at the base of a radio tower in New Hampshire. I found a number of hornets -- perhaps fifty of them -- hibernating in a compact mass on the floor near the door.

Every source I've consulted claims that social wasps do not hibernate as a colony, but that they all die except for newly mated queens that hibernate individually, each to form a new colony in the spring.

So... what did I see?

I have found similar groups of hibernating hornets in the past, most notably a large body of them inside an antenna tuning unit on Cape Cod in January several years ago.