Apple has announced the free MacBook Bottom Case Replacement Project (http://www.apple.com/support/macbook-bottomcase/) for owners of the consumer portable that has seen the rubber bottom begin to separate from the case.
Apple says it’s determined that, under certain conditions, 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. Note: If your MacBook doesn’tt exhibit any signs of this issue, no action is required on your part at this time.