Before I contact the manufacturer and have to deal with their customer support again has anyone had this problem and tried to claim under warranty and what was the outcome?

I suspect they will tell me it is not a warranty issue.

Had the laptop since July (from new). It has a full HD screen with a very bright backlight and I inspected the screen very carefully when new for any pixel problems and have a bit of OCD about spotting defects anyway.

Last week I noticed a few dark specks on the LCD when working on a report in Word. Also a few specs which look like hairs and a few slightly bright areas. This week I notice it is getting worse. The laptop is one of these ultrabook style with an aluminium case. Only places I can think that dust can get in is around the screen hinge or the 2 microphone holes at the top.

My problem or build quality issue? Already had the problem that at least one screw in the base was glued in after they stripped the thread during assembly.

It’s unusual for there to be a piece of glass in front of the LCD IME. The screen you can touch is the LCD itself.
So unless there’s something odd going on I’d say this is the LCD itself which will very much be a warranty issue.

it’s got Gorilla glass in front of the LCD.

I think the brighter zones are being caused by the pressure on the lcd.