50% overlap is not enough for good flow out. I'd go with a 75% and not pull back for the final coat.
I bet at least some of what you are seeing is the overspray at the edges of the fan pattern that is drier when it hits.

Going in two directions (across stripe first pass, along stripe second pass) will help too.
If you are shooting hood/roof/deck, you should probably set up a step at the roof so you can comfortably shoot all three at the same distance.
2000 grit may fix it for you.