I bought a 32PFL3158H/12 TV some weeks ago, i noticed some dark areas in the corners of the TV screen, especially when images with uniform color are displayed

Some examples:
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It is normal? It is a known and "acceptable" issue with the 3100 LED series or there is something wrong with the TV that i have bought?

I've also a PC monitor Philips Brilliance 228C and the image is perfect without any dark corners.

Thanks and sorry for my poor english