I once left a PODxt bean on for 10 days too, but it was covered by a quadruple-folded, thick cotton sheet. The unit was very hot and just short of "untouchable" by hand, so I'm lucky it didn't get a little warmer as it's conceivable a fire could have started.
I did worry that some components such as caps could have dried out a little, but I noticed no difference in the sound. Those earlier beans were tough.