I would guess, like most people, she judges engine response by ear. And, because of the lack of noise, she accelerated thinking she had not pressed the pedal hard enough. Mix that with the different behavior around not moving when the pedal is not pressed (unless they changed that setting), and she just did the wrong thing at the wrong time. It's just sad that, for liability reasons, it is better to force someone to prove you wrong, than just fixing the issue.