All the pictures of Brazilian '08s in both Ball and Olson show blued/dark barrel bands.
I, too, have an '08, but it's an Itajuba-manufactured '08/34. Because who doesn't want a Mauser 98 chambered in .30-'06?
How shiny are the bands? Could the rifle have possibly been used for parade functions and the bluing polished off the bands to add a little more snap & pop during formations?