looks like it maybe Galvanic corrosion.

Hopefully it isn't left over water soluble flux -- that stuff will actually eat traces if given enough time. But what you have there looks different from non-cleaned water soluble flux.
However, the green-ness of what ever is on the LVDS connector looks a bit concerning.

I previously received a question from another customer regarding the white residue that's occasionally left on the board and forwarded it to our assembly house. The response from the board assembly house was:

"This is the no clean flux residue that can happen during the SMT Reflow or wave solder process and is completely normal. It is not harmful and can be brushed off with a soft brush if he would like to."

I haven't seen a connector with the green coloring before and sent Paul's photo to the assembly house to see if they can offer an explanation. The fact that it only appears on the gold board socket and not on the attached gold cable connector suggests that it might be something left over from board assembly.

I've suggested trying to clean the connector with some alcohol and a soft cloth to see if it wipes away or if the metal is actually discolored or pitted underneath.