UP2516D, water mark?

I get this "water marked" looking line ONLY on two screens: The login screen pictured and the shutting down/updating windows screen where it is worse.

Login:

Seconds after that shot on a completely white monitor, nothing:

For the login screen, it improves to almost invisible after a short warmup of the monitor - a Dell UP2516D, btw.

The Shutting down seems to never change. I have checked the monitor with the EIZO monitor utiltiy and see nothing wrong anywhere at any color or pattern other than these screens. The back of the monitor does not seem like it could have possibly allowed any liquid inside.

Thoughts? Ideas?

Thanks.

BTW, could not find a forum for monitors other than electronics nor could i change the topic. PLEASE feel free to move this!