Default Screen Tear or Jitter on LG G2

Hey Guys, I gave my girl a g2 for her and she has been using it for about 3 months. She claims she has not dropped it. But who knows what might have really happened.

I need to know if this problem is Software or Hardware ( Motherboard or Screen).

Here is a video of it. youtu(dot)be/j6q9gOHbYZ0