Literally had him less then a day. Let him get situated turned off the lights so he wouldn't be stressed and I come back to a puddle under the hide. Is this pee? Or should I be worried?
Leopard geckos don't pee in that sense; they drop urate crystals in solid form. This is way too much fluid to have come from your gecko. My guess is he went for a swim in a water bowl and laid down under that hid afterwards. Is there any water source in the enclosure?