This should clear some things up!
From the Apple repair source page:
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.)
Products Affected
MacBook Air
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 your product is out of warranty.
If you previously paid for a repair for hinge-related issues that were not caused by accidental damage, you may be eligible for a refund. Contact Apple for more information.
Additional Information
If you plan to visit an Apple Retail store, make a reservation at the Genius Bar usinghttp://www.apple.com/retail/geniusbar/. (Available only in some countries.)
Service Provider Comments
In addition to the troubleshooting information provided in the public section of this article, use this information to assist in troubleshooting and to determine coverage for hinge-related issues:
If there is more than one inch of backlash (or free play without the hinge friction), the hinge should be replaced via display clamshell replacement.
From a closed position, open the lid approximately 30 degrees and let go. If the lid is unable to stay open from this position and closes shut, and if there are no signs of accidental damage or abuse, replace the display clamshell.
Probe to determine the issue is not due to accidental damage or abuse.
If there are signs of accidental damage or abuse, clamshell replacement is not covered under warranty.
If the clutches can still hold the display as you open it up to different angles, but the display can open up almost flat (180 degrees), it is likely a result of accidental damage or abuse.
If the customer claims that the cracked hinge was caused by accidental damage, please set up a mail-in service part Tier 2 repair. In regions where mail-in dispatch is not available, the repair should be billed to the customer.
If there are no signs of accidental damage and the computer is under warranty or covered by an AppleCare agreement, replace the display clamshell as a warranty repair. If the computer is outside of warranty or not covered under AppleCare, select symptom code Z09, MBAir Hinge Cracking.
If the computer is being dispatched to an AppleCare Repair Center with other repairs, select symptom code Z10, MBAir Hinge Cracking (Multiple Issues). By selecting the symptom code Z10, if the computer is out of warranty, the repair will be subject to flat rate fees for the non-warranted, non-top case issues to be repaired. If the computer has accidental damage that was not quoted appropriately when the dispatch was setup, a requote will be necessary.
In US and Japan, dispatch repairs to the depot when possible.