I know the scanner problem, I've got the exact same line on several of my own scans, especially when I scan them at 300dpi or up. You can actually see a very clear line on my Death Note drawing, gah D:
But still, if you didn't tell there was a line shown, I wouldn't have seen it! I really think you did and amazing job on coloring this cute . Fur and especially wool must be so hard to draw.