If the rubber surface of your MacBook has started to separate from the bottom case of the system you could be entitled to a free replacement bottom case.
A note on the Apple website reads: "Apple has determined that under certain circumstances the rubber surface on some MacBooks may separate from the bottom case of the system. MacBooks shipped between October 2009 and April 2011 may experience this issue. Apple will replace the bottom case of any affected MacBook, free of charge, that exhibits the issue."
If you have an affected MacBook, you can either take it to an Apple Store or an Apple Authorised Service Provider for assistance. Alternatively, you can order a replacement bottom case kit online.
With the kit you will receive a new bottom case, screws, a Phillips head screwdriver and instructions on how to remove the current bottom case and install the new one.
The offer covers anyone with an affected MacBook regardless or not of whether it is still under warranty. If you have suffered this issue in the past and paid for a repair, you can contact Apple for a refund.