I wonder if anyone else has encountered this: In certain situations, the passenger side wiper will "lift off" and then slap back down against the windshield. It sounds as a rock is hitting the windshield and startles the **** out of me. It has happened twice, once when I was alone and the last time when my girl was in the car with me. The first time I thought it was a rock, but she verified what happened the second time. I warily watch it now when on the highway. Some time I see is floating a bit. The only observation I could cite is that I was passing a semi on the left. Perhaps a pressure differential? If this is prevalent, what would be a suggested fix (airfoil?)?