Are you talking about the line along the weld line in this pic?

imagelinked from
http://i14.ebayimg.com/06/i/001/28/f9/c135_3.JPG
Looks to me like it "could" just be a shadow line along the weld line showing up due to camera flash or light source angle. Ask if the seller can take a better close-up pic of the area in question, without a flash.