Smudge on my S9+ screen

I bought the new samsung galaxy s9+ on contract. Amazing phone with amazing features , but there is a smudge on the lower left side of my screen that keeps coming back. I have never had this problem with my old samsung devices & this one is only a month old. I even had a screen protector on for the first two weeks. So i dont understand how this is happening. For the price i am paying i would've expected better quality.