I purchased a new macbook alum back in late November off of ebay. Recently, I've started to notice that the enter key is somewhat loose and makes a squeaking/clacking sound whenever i hit the middle part of the key, almost as if the key is not sitting tight. Now if this was any other key thats less used, I probably wouldn't have an issue with it but alas, its the most used key on a keyboard. Do you think this is something worth taking to the Apple Store to have them take a look? Everything else about my macbook is fine, so I'm hoping a simple keyboard swap would be possible. Also, since I purchased the macbook off of a ebay seller, I do not have the official sales receipt. What would I need to bring in order to show proof of purchase in that case?