Rob, I have no idea what paint.net does, but this posting is a beauty. Unless you painted the sky, I'm not sure what you manipulated. At full size I do see a slight halo effect where the sky meets the tree line; so that must be it.
The wind mills around here are tiny by comparison. You have a built in shot as soon as you turn to one of these babies. Your wind mill shots are always among my favorites. Please ship one over here. Send it C.O.D. and I'll pay you back the second Tuesday of next week.