I got my FW back in November and the case had a bit of a musty odour. The machine still has a bit of an odour when I first start using it. It does not really bother me; I figure if I leave it sitting in my sewing space long enough (and not in the case), maybe the smell will eventually go away.
It just occured to me that maybe you could try Febreeze in the case. I have not tried this myself, but you never know. Good luck!