Unhappy [Q] Galaxy S4 Screen Fluctuate or Glitching

Dear XDA and all friends i have bought samung s4 and what i find that some time when doing lock screen or on the display fluctuate or glitch from the bottom, today i saw that i connect my mobile to my car stereo through Bluetooth and when i am trying to call the screen light goes down and when i press any where in screen the display fluctuate ... any ody know some thing i am trying to capture that moment .