Hi and welcome to YT
. It could be that she has allergies and her throat/nose is dry...do you see any other signs of allergies? Otherwise, it could also be age related. Just be sure the noise isn't sounding like wheezing / difficulty breathing, ya know...? If that would be the case, you'd want to get to the vet asap. At any rate, you may want to have a vet check it out anyway...if you do, make sure you capture the sound/breathing on your phone's video so that you can show the vet...as she may not make the sound while at the vet's office.