I've had my rMBP a couple weeks now without problem except for the "B" key giving me a little resistance when pressing it (compared to the others). I pressed on it really hard and then I knew something was wrong because it made a noise when I pressed it. After removing the plastic key, I noticed that a tiny piece of the plastic underneath. I removed it thinking that was the issue only to see an extremely micro screw. The real culprit. Now the "B" key functions fine. I'm not really worried about the tiny plastic which was probably a result of pressing down on the key really hard which shaved off a little bit of it. I'm worried about this micro screw. It's not a normal screw. I don't knew where it came from. My guess is that during the manufacturing process it found it's way on to the aluminum. If that's the case, I'm fine with that' But there is an older thread for the exact same thing with the MBA. One member even said the keys were fine and later on tough to press, showing the same problem. I'm worried about this micro screw. Everything else is perfect, but I'm worried about where it came from.