Hi Colleen :)
I am guessing your orange ferret was previously white?  Newton (my
beautiful black-eyed-white) turns orange this time every year after a
massive coat change, most predominantly down her spine and tail.  Since
it happens every year at the same time and her food never changes I
always figured it was simply genetic.
 
Good luck integrating your fuzzies
 
Jen
Newton, Dobie, Fig, Mojo and Maggie
[Posted in FML issue 3209]