Apple published a TechNote related to the MacBook Air hinges: http://support.apple.com/kb/ts2948In summary Apple will replace at no charge hinges of some MacBook Air, if you experience the following problems:
Symptoms
Learn what you can do if you experience one or more of these issues with the hinges on your MacBook Air.
Unable to close lid completely.
Broken or cracked plastic near one or both of the hinges.
More than one inch (2.54cm) of free play while opening or closing the lid.
Lid falls freely into closed position from a 30-degree open position. (From a closed position, open the lid approximately 30 degrees and let go.)
Resolution
You can take your MacBook Air to an Apple-Authorized Service Provider or Apple Retail Store for evaluation and repair if necessary, even if you
