Gray looking smudge on iPhone 6 display

Just bought my iPhone six and received it a couple of days ago. I noticed that when my screen is on a white background, like in Notes, a darker gray looking smudge (about 1 1/2" long) is in the middle of the screen. I attempted to wipe the screen and the case's screen protector to ensure it wasn't a surface smudge and sure enough it is not on the surface and it is still present without the case on. Very frustrating. I have an appointment with the Genius Bar tomorrow... hoping they will replace it for me. Anyone else having issues like this or have had a success story with the Genius Bar with a situation like this?