WE've found that there seem to be as many reasons that a ferret nips as there
are nipping ferrets, but from your discription You may have the right idea -
the ferret may be associating being near your husband's face with being
whacked.
 
The training approach that seems to work best with our occasional shelter
nippers is to scruff them behind the neck, shake them hard (but not too hard
that you injure them, just enough that they think Mom is back and doesn't
like what her kid has done) and yell at them, like, "NO!  YOU WILL NOT DO
THAT!  NO! DO YOU UNDERSTAND!  NO!"  The words besides "no" don't seem to be
as important.  My wife is a master of this.  I've seen her take a ferret
given us by another shelter that was ready to have it put down because they
couldn't break it from biting.  Inside two weeks, the ferrets was as sweet as
could be.
 
No guarantees, but it works for us.
 
Dick Bossart
[Posted in FML issue 1081]