I've seen that before. Have you sharpened your image in photoshop? or cut and pasted it somehow? It looks like an antialiasing line that happens on the edge of an image. Open the image in photoshop and zoom in real close to the left and right edges of your image. you may see the line is there. When this image wraps inside a tour those two edges meet and that line appears. I'm not sure how Panoweaver would be causing it though.