Tweak... I don't know how I missed this thread! I am soo sorry... (a little late I know.)
I'm glad to hear that Jynx is doing well!
I have the same problem with one of my ferrets (Tigger). Everyonce in a while she will cough like that & upon vet examination nothing was found... I was told she she may have potentially come from a bad blood line with a weak respritory system, so the ferretlax (or vasoline) is a vital thing to keep in my house for her. I've found 95% of the time if she starts coughing I give her some lax & she stops.
Keep us updated on how Jynx is doing! (a recent picture could be good