Like the title says, been living here a little while, was out on a walk with our 9 month old and the sunset was just about perfectly parallel/in line with the roof slope and exposed this to me for the first time.

We are in Southeast Pennsylvania, the roof is about 7 years old - no leaks that I’m aware off. Could this be from ice damming last year? That is the north facing roof that gets very little direct sunlight.