I've been curious about that too. It's definitely not a burn - it's a solid little kink, and the scales around it are all fine. It only became prominent after his last shed.
I've been looking around for pics of other males with that sort of kink.
My first fear was something like MBD causing bad bone formation, but his limbs and back are good, and the casque is firm.
I asked Chris about it, and he said that some chams just develop little kinks like that.
So I'll keep an eye on it, but for now I guess it's just something that adds to his character...