I am someone who has molded the front mudflaps with a heat gun and a block of wood. The problem is that the mudflaps are close enough to the hot engine and hot road, that the natural heat around the flaps eventually reforms them back into their original shape that rubs.Nice work. Did you damage the stock mud guard? A lot of people running 33-34” mold the factory part with heat and a block of wood.
I think this happens to the flaps because they are a very soft plastic.