I found a charging device hanging on to my extension chord, inside my electronics bag when I got home and unpacked.
I was parked/camping at the N-40 by the Cafe and EAA souvenir store. This is where I generally plugged in next to the ATM machine, by the telephone pole, while I was there for the week.
I think it is a battery pack recharger.
I know this may be a long shot, but I am not sure what else to do but ask if any of you are missing it. I don't know if EAA has some sort of "after the show" lost and found, but this device is definitely not mine.