Leopard Gecko Ate Terrarium Moss - Anyone Else Experience This?

Our adult leopard gecko, "Sachi" had not eaten voluntarily for a few days, despite the fact that he'd just finished shedding and should've been plenty hungry. Last night, he came out of his hide box and passed a bit of waste, then went back inside to get the rest out.

As of this afternoon, he'd still not pooped, and he was trying to pull it out of him in frustration. My brother thought he might have a cricket exoskeleton stuck or something and thankfully had the idea to soak Sachi to try to make things easier. It worked. Turned out that basically Sachi's entire system had been full of terrarium moss from his wet hide box: one big one that pulled apart into two pieces. End-to-end, they are about eight inches, about as long as him. We're guessing he ate it accidentally with his skin the last time he shed.

Has anyone else experiecned anything like that? Any ideas on what to expect health wise? His terrarium moss was removed from his box and replaced with wet paper towels, and Sachi has a reptile-specialist appointment for Tuesday. I honestly don't understand how he isn't dead now, but he seems okay considering and lapped up a bit of a reptile nutrition/electrolyte supplement he was offered to help recovery from the stress.