Sharp exhaling sound

[marissab]

I know tortoises exhale when they go into their shells, however Luigi has been making a sharp exhaling sound every once in a while. His habitat is in my room, so sometimes when I go to sleep I can hear him making these noises. I think it came from his nose. Usually he makes this noise when I'm nowhere near him, or even out of the room. He seems otherwise healthy, with normal eating habits and bowel movements, digging in his pen and climbing around. I'm still worried about this. He was treated about a month ago because he was blowing bubbles out of his nose, and has fully recovered however this worries me. Do Russians usually make a noise like this on a regular basis?