Does that mean, dkwatts, that you don't have my problem? Well then, thanks for the solidarity.

Thanks for the suggestions, Jon. I didn't leave the tablet outside, but I did just take it on its first major trip--up into the rockies in CO. The battery appear fine, and there are no similar symptoms with the internal slot.

This is f-ing weird. And scary: I don't want my tablet to leak to death!