Display discoloration after 2 months usage

I fitted a new Samsung LCD two months ago now the customer has brought it back with heavy discoloration to the lcd.

I used an original Samsung LCD service pack, so its not a cheap Chinese copy.

To me it looks as if it's has some sort of pressure on it but the customer claims it hasn't.

I give a 3 month warranty with all my repairs and if it was something caused by my work then I'd swap the screen under the warranty without hesitation.

See what you think from the picture