Green tint on screen

Hey guys,

We just got back 30 boards from being loaded onto our PCB and on a few of the boards we noticed that when we connected a tested LCD that the black appears greenish. When we reconnect that screen to another board the screen displays black vs the green tint. Should I suspect pins on the display header or could something else be causing this? Thank you very much in advance.

There is about 30 signals going to the display. Check those connections