I noticed when I Press the sleep wake button on my iPhone 6, instead of the screen turning on and going to the lock screen, the screen has a gradual flicker to white then black, then the lock screen comes up. pressing the button again turns the screen off, and pressing it again turns the screen on normally without flickering. However after turning the screen off and waiting for about 5 minutes, then pressing the sleep/wake button, the screen gradually flickers to white, then black, then brings up the lock screen. It's as if the phone when the screen is cooled down or off for an extended period of time, this behavior occurs. I notice it is most easily observed in a dark/pitch black environment. Anyone else notice this or are you not seeing this? Is this an issue?