But In-game it doesn't glow. So it doesn't matter.
He's talking about the painful-looking yellow piss stain floating around the hair of the face.
I am sure you can notice this in-game but probably just slightly since faces and decals generally have a 4-8 pixel border (not sure how many pixel but its seems about right)
Usually everyone does some sort of face, decal, or print edit for their first add-on because they are easy to make. That being said, keep practicing and I'm sure you will get better!
Good luck!