Hi, i have a similar issue on my mid 2014 Macbook pro 15" 2,5ghz NVIDIa Geforce 750m 2gb, some red pixels vertically displaced right on my screen.
I had an appointment in a genius bar and they told me is a display failure, eventually i should change the screen. The Macbook pro is out of warranty and the price of replacement is high.
I didn't expect after three years this hardware problems, i have a 17" powerbook g4 more e10 years old with a perfect screen and 4 years ago with a 2008 macbook pro out of warranty, Apple changed for free a logic board for hardware problems.
I thought they would change for free the display for this hardware failure, but the Macbook pro is out of warranty and they did't
This new retina displays seams give problems also after few years of use
So if your macbook air is in warranty ask an appointment in a genius bar and perhaps they will change display for free.