> Anybody experience an issue like this before...

I have, but only when I've gotten something on the monitor (like liquid droplets or thin hairs placed just right) that did funny things. Have you carefully cleaned your screen recently?

If it's not crud on the screen, then my vaguely-educated layman's guess based on the symptoms is that some part of the light guide layer between the tiny shutters and external surface of the screen [0] has gotten damaged somehow.

[0] Would this be called a polarizer? I'm not sure.