Returning from vegas Sunday, we noticed the brakes chatter with any foot pressure beyond just lighting the taillights at fwy speeds. Braking other than that is normal. This only occurs at fwy speeds. I took the car to MB this am and there test drive diagnosis is calipers and pads due to the wheel cleaner acid used at car wash. Anyone ever herd of such a thing? it’s been to the car wash twice, months ago.