First, does she seem to have any health problems? Weight loss, lack of appetite/thirst, sneezing, itching, head tilt? If she seems healthy, then it is probably because of stress. Have you moved her recently into a cage with new mice? If so, I'd recommend removing her from that cage and putting her in her own cage. If she seems to have any health problems, make an appointment with the vet and let him/her know your concerns about her behavior.
She otherwise seems incredibly healthy. Her coat is much smoother; she's beautiful! She started making "stress noises" after I purchased 3 newcage mates a couple weeks ago. She is soft-hearted and it made her a bullying target. I bought a new cage and put the main bully mouse in it. I did not want the bully to live alone, so I used one of my older accessories to add some floor space and added a bigger mouse that she could not pick on (thay are also aunt/neice, so it works fine). In the main cage is my three original mice (including the mouse in question) and one of the new mice. The new mouse got in several tiffs with the mouse in question over the wheel, and then the circling started.
I can not put her into the other cage, because there is not enough room for her and even if there were, they'd rip her apart! Money is no object with my mice, never has been. But I just lost my job and currently don't have the resources for a new cage

. I'd love to buy a little secluded "cool-down" zone for them. Maybe I can use my last paycheck (which should have arrived LAST WEEK) when I get it...
I don't worry about the "stress noises" (the snuffling/puffing), because I gave her a round of Baytril for it, and I also have another mouse who has always made the same noises (and still is not dead after 4 months). Sometimes when the tissues settles after a past URI, the noises will continue, and it will seem like a completely new infection when it is not really...
If she shows any new symptoms (gooey eyes/ears, lethargy, whatever), I will try and convince my boyfriend to take her to the vet. It is his favorite mouse and he is worried too, so that won't be hard; he's the daddy after all.