Slippery:
Nate,
She is sulking. You went away and stuck her in a run with lots and lots of strange dogs and strange people coming and going. She is a little uncertain about what happened.
We get the same thing whenever we put our menagerie into kennels. They get over it soon enough.
I agree that's the most likely case.
I will say though that heat DOES significantly affect dogs, and people need to be much more careful about their dogs in hot weather. Of course, the one that *should* be obvious to most people is not leaving your dog in a car in the summer. Even with the windows rolled partway down, it only takes a few minutes for the heat to get unbearable inside a car on a sunny summer day. There was a case here last summer where some young guy went to stop by his technical school to pick up some papers on a sunny day (temps in the mid 80s I think), and decided to take his dog with him. He figured he'd only be a couple minutes, and left the windows rolled partway down. He couldn't get his papers right away, but went back outside after about 10 minutes - but by then his dog was already going into heat stroke. Even though he let the dog out and tried cooling him down with water (paramedics arrived in minutes), the dog still died.
Point being - be very very careful with your dogs in the summer. Most dogs aren't designed to handle heat. They can't sweat like us, so only cool themselves by panting or by releasing some heat through their pads. Panting in a hot car doesn't do squat for cooling them.
On hot days, we leave our dogs inside in the AC (with the windows well covered up to keep it cool), and only let them out in the yard briefly.