I think he's been chewing tobacco...just kidding!It really does just look like he stuffed a little substrate* in the front of his mouth...and before I'd take him
ANYWHERE (exposing him to chill temps & germs from other herps!) I'd use a blunt object (like a tongue depressor) to open his mouth & have a look, & maybe
flush his mouth out w/ a bit of water. (*since he was just fed, it could also be rodent poo that didn't get swallowed with the rodent itself & tends to be stuck on
the back end...)