It could be or damage to the outside scales which then can lead to mouth rot issues. Can you get a picture of him gaping and the inside of the top jaw there?
So I am not seeing any sign of mouth rot on that top jaw line. Normal mouth coloring. Looks like a tiny injury to the scale though. It is not something I would be rushing to a vet for but I would keep an eye on the area. When he gapes at you look at the inside right where the injury is. Make sure it is not getting puffy or red.
He is a handsome boy.