I remember a previous poster here had the same problem. He got it replaced, but had to talk it out with the Genius.
That was me.
Indeed, I got a replacement, but it took quite a bit of negotiation. The replacement doesn't have this problem.
One theory is that the magnet was too strong in the latch, thus pulling the lid closed too tightly. My replacement MB does not have as strong a magnet.
The other theory is that the rubber gasket surrounding the screen was not protruding far enough, allowing the lid to close too closely to the body. If you run your finger around the gasket, you should feel it raised about 1mm above the glass, all around the screen. On my 1st one, the gasket felt a bit too flush to the screen.
Both issues may have been a factor. There is very little room for error between the key tops and the screen. .5mm can make the difference between the keys touching or clearing the screen.
My advice would be to make a genius bar appointment, but show up 30 min. early and don't check in right away. Use that time to inspect the floor models and compare the gasket and magnet to yours. I suspect you will find differences. This will arm you with information when your appointment comes. If the Genius or manager (I had to escalate the issue to a manager) tries to play it off as a non-issue, ask him/her to look at the floor models compared to yours.
You do not need to bring the box, but it wouldn't hurt. If they decide to let you exchange it, you will be given a brand new computer, and if you bring your box and all accessories, you will simply swap with them one for one.
Be sure to do a backup before you go, then wipe your drive. Tell them you've already wiped your drive if they try to avoid making an exchange.
Also be warned that if you do get an exchange, the replacement could have other issues. My replacement was perfect. Others have not been as lucky. Be sure to check it out BEFORE you leave the store, as waiting to get home could result in yet another visit to the Genius Bar if there's a problem.
Good luck.
