I have, in the past purchased used CDs off Amazon to good satisfaction, meaning they are usually in the shape the seller says they're in, arriving in a timely manner. On at least two occasions, I've received CDs with library stickers on them...I'm guessing these have been checked out, then sold. Should I contact Amazon, and return the CDs? Should I bring this up to the seller? Both these CDs were purchased from reputable sellers, according to Amazon's rating system, something I usually pay attention to.