Could just be dry skin.

if you dont see any other signs of infection, or bubbles and such, or TOO MUCH moisture in the mouth, id just make sure your temps are right, humidity spot on, and go from there.

Vet is never a bad idea if you are truly worried though, but i see many people overreacting when they hear a whistle or pop come from their snake randomly * or after a soak*, only to report later after a shed, * or the snake dried off* it went away.