Looks like a line of LEDs have gone.
I have the same problem with a 2010 MBP with Hi-Res anti-glare screen where a blue line goes from top-to-bottom on the left side of the screen and is visible on dark backgrounds (not so visible on light backgrounds).
Annoying but since the MBP is OOW, it will cost at least $700-$800 to replace (maybe more since it's hi-res AG, previously had to replace another MBP screen which was $700).
Since its still under warranty and you have Applecare, take it back to Apple and they would likely replace it.