I haven't read your other post (at least I don't think I have, my memory sucks) but one of my ferrets does this quite a lot. She has been a part of the group for many years, but sometimes she just gets p****d off with one of the others, even if they just walk past her. This is when she hisses. Mine quite often let their glands off (the smell) and sometimes it is during play. Are your ferrets playing rough? Sometimes when mine get a little too rough the smell comes about. I also had one that hissed when he had a ball.... he would choose a plastic ball, pick it up, run off and hide in a corner and just sit there hissing. I honestly don't think it is anything much to worry about, just keep an eye on their playing and make sure that the other ferret isn't being overly rough with her.

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Proud owner of 4 dogs--Cody, Babe, Ella and Bridie. 2 cats - Klimt and Mia, 5 ferrets -- Leola, Drucilla, Tommy, Spike and Pippin and 1 horse -- Puzzle

Ferrets skunk 'cos they can.
Sometimes it's because they are excited, sometimes it's because they got picked up. or pounced upon, or sleeping, or....
We get 2 different kinds of skunky smell here. Sometimes it is a very acrid, nose burning kind of stench, and the other is just like extremely strong poo kind of smell.

My Kev is a hissy mister. He hisses 'cos he doesn't want to play, or he's tired. He's been known to hiss because he wants a biscuit!

Hissing is usually a 'buggar off and leave me alone' kind of noise.