Originally posted by DaBrain
Ok... I didn't really understand it, but it's fixed now. 
Ok. Hopefully, this'll help you. Notice how UVing works? While it may normally seem that you are working within the constraints of a single image's borders, it is not that way at all.
The number 1 represents how the image is tiled.
See the green rectangle? Where it overhangs off the edge of the tile? When a peice of UVing overhangs off the edge of the image, it is, essentially, looping over to the begining again. (see the green triangle?)
Now imagine that the blue pie-slice-shaped section is your shockwave's UV selection. If it goes too far over to either the right, or the left, it will, in essense, do just as the green corner did from the green rectangle. Which is why you had the seams. Those seams were the edge of the orange tile abruptly ending, and the begining of the next tile (the same map) which I assume is black.
Understand?