Strange lines on 27" cinema display

I sold my display port 27" cinema display monitor to a friend and it now has strange lines appearing on it. They don't look like graphic glitches as they're not uniform in width and don't run the full height of the screen. Anyone have any idea what they could be? Here is a picture he took of it. It's connected to a PC.

E-Bay is looking good to me for my next equipment sale!😁