When I turn on the phone, the screen seems to flicker quickly. This happens on the boot up screen. So, the screen is black with the white apple in the middle. The screen jitters a bit and a grayish line quickly jumps across the bottom of the screen while the phone is booting up. Seems to work fine after boot up. Anyone else seeing this happen? I swapped out my phone once from the 64GB version to the 256GB version and both models do this.