A customer said one side felt heavier after I finished a fade today. How can I fix it on the spot without starting over?

After finishing a men's fade today, the customer felt the area behind his right ear looked heavier. There was indeed a bit of a shadow in the mirror, but it wasn't because the line wasn't blended; it was due to his skull shape and hair whorl direction creating a visual illusion of thickness. Instead of immediately fading it higher, I first used a comb to pull both sides up at the same angle to…