If your MacBook is exhibiting discoloration on the top case after some use, please contact AppleCare for service.We have obtained some additional and exclusive information:
Apple has identified the problem. The plastic composition used in the past has been modified, and new cases are being produced. However, not all CMAA have received the new case, so do not rush to get your MB case exchanged, you might get the same problem again, or your notebook might be stacked for days or weeks before the modified case arrived.
In a couple of weeks, the case exchange will be performed in a couple of hours.
