When sound first started scraping, I was very concerned. Heard loud noise, like something broke loose, then more screeching for a couple blocks. Stopped to check problem, saw nothing but called dealer to complain but salesman not available. Started to go to nearest Chevrolet dealer and sound stopped. Figured a 'dirt clod ' must have broken loose and got caught in wheel or brake area as I had driven through a graveled mud puddle the night before.