It turns out, my case was responsible for my weird screen issue.
I used to use the Yesoo case for the 1520 and the screen issue occurred periodically, especially in landscape mode while I read lying down.
Amazon.com: YESOO? Sexy Ultra Slim Fit Frosted Case Anti-Scratch Matte Premium Cover Nokia Lumia 1520 (Lumia 1520, Gray): Cell Phones & Accessories
I bought a tempered glass screen protector but it didn't cover the entire screen so I bought the following case.
Amazon.com: MOfi brand Flip Leather Case Slim Cover for Nokia Lumia 1520 (black): Cell Phones & Accessories
This case is super tight and removing the phone is a hassle. Once i had my phone in this case, the weird screen issue was multiplied 10 times.
It happened in portrait mode, landscape mode, standing, sitting, laying down. Didn't matter, the problem was really bad, sometimes the screen wouldn't register my touch even right after unlocking the phone. Sometimes i would have to lock/unlock multiple times. So i trashed the case and bought the nokia cp -623 and haven't had this problem since.
I think Nokia knew about this, that's why the phone only secures/ "clicks" at the corners of this case and not the top/bottom or sides. I think when pressure is applied to the top/bottom and sides is what causes these screen issues.