shift into park

Hi Everyone: My 2016 MS 90D (50,000 miles) has begun to emit a VERY loud high pitched squealing noise lasting less than a second, every time that I shift into Drive or Park. It's coming from the rear of the car. It sounds like an air wrench. Otherwise the car drives fine and there is no noise...

When I owned an ICE, I would always turn off the engine when I knew I would be stopped at a light for > 1 minute. With my MS, I don't have to worry about wasting energy at a light. But when I'm headed uphill at a long light, I still shift into "Park" so I don't have to hold my foot on the...