This is probably normal but figured I'd ask. I have a bike with a Bafang Ultra. It only has about 150 miles on it. When I stop pedaling and the assist disengages, I hear a quick faint spinning noise from the motor. This happens every time. It only lasts a second or so and just sounds like a gear slowing down. Is this a normal noise when the motor/assist disengages? I don't remember hearing this when I first got the bike, before the snow, but I'm wondering if I'm just noticing it now since it's a lot quieter outside with the snow. Thanks.