I installed the replacement screen (digitizer Assembly + front housing) and noticed immediately a 'shadow' in the upper left corner of the screen.

(image uploader doesn't work)

It's a dark area (~1cm2) on the screen that has a soft edge and is darkest at the screen's edge. 

The screen+housing came pre-assembled so I doubt there was any mishandling on my behalf.

The installation was otherwise smooth and everything else functions as before.

So, is the screen defective?

Is there a way to correct this or steps to troubleshoot the issue?

Thanks,

Chris