i'm having the same issue! happens almost every time i brake on my fourth gen. it's a very quiet noise that sounds like a computerized stepping motor. only lasts for about a second. it's annoying but i usually have the radio on so i can't hear it. braking is not affected.
Yeah, I've thought about this too. I feel it right under my feet when at a stop light. Goes away while driving. Sometimes it feels faster than others. I thought my motor was messed up!
