Doubtful it is hardware
I have been having this problem since the 4.3 update. It usually only happens when the screen dims down due to screen timeout. Then it will start to get worse and project the flicker at regular brightness. A reboot usually fixes the problem or lessens it for a period of time.
I have tried with and without my live wallpaper, auto brightness on and off. Some people have recommended a factory reset to see if that clears it, but I have not been willing to do that yet since I have data that I do not want to loose and have not had the time to really troubleshoot. I am completely stock.
This has been driving me crazy for a while now. If you do factory reboot please post if makes a difference.