As a followup, the car's whirring got to the point of occurring after every braking. On the way to the dealer for diagnosis, it hit limp mode. It's not fun flooring the gas with a 5000 RPM red line and not hitting more than 25mph up a hill!
They at first didn't believe that it was the sensor, until the tech heard the pump come on when I hit the brakes in park. Supposedly, it's only supposed to come on during high speeds.
In the end, the replacement sensor was in California, and with only a day's downtime, all is well and fixed.
I asked about corrosive brake fluid on the sensor, but supposedly, it was clean.