Ok, the EXACT same thing happened to me, although I sneezed all over the screen (gross) and then wiped it off with a windex covered paper towel. Then followed up with a damp microfiber towel to remove smudges. There was no way that water could have gotten in nor the windex.
So I raise you this question; did you use a microfiber cloth, and are you in a dry-cold or a dry-hot otherwise low humidity climate.
The reason I ask, theoretically if you did use a microfiber, had the computer on, and rubbed back and forth across the screen several times, you may have created static electricity, which may have interfered with the screen.
I found that after doing several power cycles (command+control+p+r+power) the green tint completely disappeared. I also noticed that the cat hair that flies around my house is not sticking to the screen anymore....
Food for thought
FYI purchased NOV/2014