A few days ago, I started noticing a sufficiently loud grinding (feels metal on metal) noise coming from the passenger side rear wheel intermittently. Looked like it was coming from the caliper area when I took a closer look (while my wife as slowly backing up the car). It is not very consistent, appears once or twice a day, and disappears when I apply the brake. I jacked up the car to see if something got stuck in the wheel but couldn't find anything. I am not sure if worn out brakes will cause this kind of issue. Does anyone have any suggestion or opinion before I shell out money at the dealer?