None of my YB, Asphalt, or any other YB complex morphs have that marking, not even with Enchi in there, and I have quite a few. Could be something unique to him, though I have seen markings like that before in other morphs. Do you want to post some pics of his headstamp, side pattern, and dorsal to see if there is anything else that might stand out to us that you might have overlooked? Those markings on his chin look a little like what YB complex stuff does to the belly, so perhaps some other morph pushed more color to his lower face to give that end result mixed with YB/Asphalt.