I'm no expert,
by any stretch of the imagination, but it appears to me that, rather than fading--i.e., going away--the red in this corn snake is actually becoming more apparent and deepening in color. That is to say, the red that was there in the first photo is getting more red, deeper, darker, and more prominent, just the opposite of fading.
Personally--and, again, I'm no expert--it looks like you have one of those Ruby Freckled corns.