Vapoor eyes er, I was looking into this the other day and still have a reference handy that says neither Kanthal or Nichrome rust easily. If it really is rust, IMO it's from the tube. Which is weird because as you say they should be plating it if it's not SS.
Weird and thanks for that. Maybe it's juice gunk disguised as rust. I know they flip between using brass or copper as the base and then plating it.
Here's something I found about the composition of Kanthal:
http://www.e-cigarette-forum.com/fo.../320042-resistance-wire-kanthal-nichrome.html