Thin horizontal white lines on iPad mini

Scenario: The iPad mini 4 is in portrait mode.

occasionally I will get, maybe, between 5 and 10 thin horizontal white lines going across the bottom of my iPad screen (just above the home but but more recently across the top too.) I found that if I lock the iPad and open it back again the lines generally go away. Sometimes I have to do it more than once but it always goes away after I do that. I’ve never really dropped the iPad nor have I left it in any extreme temperatures or in humidity that would do harm to the electronics. It just started doing it one day.

Can anyone give me any insight as to what might be causing this? I’ve tried googling it but the closest thing I’ve seen is lines running vertically, about the with of an app icon.

Thanks in advance.