Acer predator xb321hk monitor has dark spot after repair

jaspar4

Hello , i have an acer predator xb321hk monitor that i had sent in for repair because of dead pixels and a weird artifact showing up at random times.When the monitor came back i noticed that the lcd was changed and  everything was fine , except for a dark fingerprint like spot on the panel.I tried to clean it with a soft cloth and cleaning monitor liquid with no success , this seems to be on the inside of the monitor.The spot is mostly visible when the area around it is of the same colour (all white etc. , however not visible when black colour in the area because its dark).The shape of the spot is nearly the size of a fingerprint and below it there is another smaller nearly invisible dark spot.My guess is that while the lcd was getting changed someone touched it from the inside and it was put in place while dirty.Does the waranty cover another check and fix for my problem?Could those dark spots be something worse?Thank you.