Q: Horizontal Pixel lines in retina

My 3 months old retina had screen replaced for multiple dead pixel. But the new replacement screen has horizontal pixel lines visible under light color specially blue and orange. As a web and graphic designer this is very annoying but the official mac dealers in my country refuses to acknowledge it saying they have never heard of this problem even though one of them acknowledge he sees it too. I m currently trying to install maverick in external hd to see if it is yosemite problem. Any help? I am from nepal.