cyan vertical line on the screen of Nokia Lumia 920 at&t

If it's not physically broken and there's odd colored line on the screen, that means the screen is defective and should be under warranty.

Closest Nokia Care should change the screen free of charge. I had my proximity sensor cleaned for free, since the device doesn't have any physical damage.
 
Hey, I have the same, exact problem on mine. It came up after an update (forgot which one).

Guessing it's a software thing :/