A very spurious CSI investigation afterwards pointed to a car charger cord being underneath the cup when I put it in the holder. It is currently being detained for questioning.
While I didn't get to drink any of it, I did, however, get to take a bucket full of hose water and knockoff Pine-Sol and scrub away at it in the cold darkness.
None of this is to say that I didn't stop a second time to get a second drink. Anyone from Pennsylvania will tell you that Sheetz fountain drinks at just the right temperature are worth making any number of stops.