When backing out today I noticed a pretty bad scrapping sound. It went away so I assumed that it was just a trashcan lid that I had run over. Tonight my mom came home and noticed a panel on the street. After looking at this thread http://priuschat.com/forums/gen-iii-2010-prius-main-forum/68549-photos-taken-bottom-my-prius.html I identified the piece that fell off. 1. How concerned should I be about replacing it? There appears to be some weird thing on the other side. 2. Cost to replace?