Lumia 920 black matte color splash

[kostas023]

Hi, i have a lumia 920 black matte 5 months now and from the day i bought it i had it in an original nokia cyan case all the time.
One day i took it off the case and i saw that the color on the back have some splash.
Look the picture and tell me if anyone have the same problem and if you found any way to clean it.

 

[DBDev]

The same thing happened on my 800 when I took off the cover. It is better now, but it is still not gone after about half a year

 

[AndrewL920]

I wonder what causes this. I am currently using a white gel case for my white 920