Do you use the cover that came with it?
if yes then it depends - the color is supposed to be through and through but its possible in cases where its not a scratch that the color just faded due to exposure to either some corrosive...

Do you think it is a possibility that its not the original?
Quite easy to make a replica/duplicate part assembly....

To state the obvious: If you're still under warranty(which you should be, its not been a year since it was launched), I think it would be right to exercise it.