Ipad pro 11 inch has a black smudge spot on the screen

Hey i have recently bought a ipad pro 11 inch about 3 months back. A week ago i noticed a black smudge spot on the screen. It is only visible when the screen is turned off or with dark images. I tried wiping with microfiber cloth but it didn't go away and the spot seems to collect more fingerprint than the rest. Does ipad pro has some kind of special coating ? But 3 months is too little time for it to rub off