Several MacBooks experience discoloration

Several quarters who own Apple’s new MacBook have noticed some discoloration after a fortnight’s usage. This has raised concerns that the discoloration is due to a heat-related issue, while others are speculating a chemical reaction within the MacBook’s plastic enclosure as seen in the Toshiba Satellite P30 that uses similar material. Off-the-shelf cleaning agents are not effective to wipe the problem away. This problem has been categorized as a cosmetic issue, putting it out of the warranty radar. Do any of our readers have a picture to verify this?