Weird line?

I need urgent help here. I've created a number of different floor tiles so far and never had this problem before. I am working now on this new set and suddenly some weird line appears where two tiles meet when I place one tile and than second next to it but rotated. This line no matter how far away point of view is (cam) always looks sharp and not blurred so it cannot be baked in the texture image. I also checked all maps, diffuse, normal and specular multiple times and there is absolutely nothing that would indicate that line. Can someone help what this problem might be?