That herringbone stitch I came across while shopping at Ninian haunted me until I purchased this Racket scarf from them. It has the same pattern.
With a closer view you can perhaps make out the zig-zag traveling stockinette stitches. It looks the same on both sides so it's some sort of interlocking double knit stitch. It's still a mystery to me how this is done. I couldn't find it in any stitch book and haven't found time to decipher it. I'm pretty sure it's machine made.
Check out the cute tag
on the side.