Its kind of hard to tell from your screenshot whether this is being caused by your texture or FPSC, it might be that you are using low lightmapping settings. What I would do if doing this kind of texture is to place the gradient in the center. so you don't get crossing of the seams in the middle the way you have it.
Up your lightmapping and let us see the result if it looks the same then its your texture which isn't as seamless as first thought. If you increase the canvas size in your image editing prog and lay the seamless textures side by side do they appear ok?
Awesome! Its one of those threads.
