Chin making weird noise.

My female chin Squeaker​ has been making a weird noise. It sounds like a cat trying to cough up a hair ball. She's been doing it since I got her almost a year ago. I took her to the vet for a check up and about the only thing I learned that day was that Squeaker is a female. When we bought her we were told she was a male. The vet said she's healthy. Has anyone else ever heard this noise? My other chin doesn't make it.