weird worm shaped whiter line on screen

I recently received a 1.5 ghz refurbed model, which so far i love. however, i just noticed yesterday a strange whiteish line in the middle of the screen. it is super faint, but appears as a very slightly lighter shade of any lightish color that is in that area of the screen. it is most noticible on a white backround. it is not an spot like area but rather a wiggly worm or snake shaped line that appears to be several pixels wide and about 1/3 inch long, vertically on the screen, it is not on the surface of the screen, but appears to be behind the plastic screen itself.

any tips on what might be causing this? the screen is perfect besides this so if there might be someway to fix it without sending the machine back, that would be great. it is not very noticible, but it is in the middle of the screen so i am staring at all the time.