For the last couple weeks, I've been getting a bad film developing on the inside of the windshield at both lower corners, like something is blowing out of the far edges of the defroster vents. I clean it off but 2 days later, it starts coming back? It started shortly after I changed the water pump, hoses and thermostat housing. I changed them because the water pump had developed a small leak around the shaft so it wasn't like I had a major eruption of coolant in the engine bay. I'm hoping the film may just be residual coolant getting cooked off the engine but there is absolutely no odor in the car (coolant always has a distinct smell). Anybody want to venture any guesses? By the way, it's a 1998 M3 sedan if it helps.