Ross, that might actually be an icon cache issue with the Shelf. Try restarting WorkShelf to see if that particular Steel Dragon folder icon remains the same.
Should have read the whole thread before replying.
If you are having problems with that particular icon elsewhere and you have already rebooted (you have, haven't you? lol) then this has nothing to do with the Shelf.
Normally the Shelf will rebuild its internal icon cache when there is a system wide change, but that particular icon could have gotten 'stuck', which is why I suggested restarting WorkShelf.