Macbook Air: Half of screen is white??!?!?!

Just purchased a 13" MacBook Air 6 months ago - have never dropped it, spilled on it, it's rarely left my desk....Suddenly the screen display is have white with vertical lines going down the center. When I plug it into an external display, I can see the full screen with not disruptions. The earliest appointment I could schedule with Genius Bar is in 3 days (a lifetime to a grad student). Any suggestions for causes/fixes/cost of repair?