No that is not mouth rot or anything to worry about for that matter. There was a thread awhile back about this as a members chameleon shed and the shed from the corners of the mouth were actually yellow. One of the vets on here explained why but I cannot remember what was said. I do know it is not mouth rot though.
Clouseau had mouth rot and his mouth did not look like that; his bottom jaw protruded slightly more than his upper jaw. The discoloration from the infection was inside his mouth. I also do not think what your are noticing in the pictures shows anything amiss.