I have a couple of carpets that wheeze or whistle sporadically. They have done it since hatchlings and are fit, eating well and are 4 and 5 years old each now.
One of them does it more than the other, Particularly around shed time. Once the nose plugs come away he clears up nicely.
The other one is more obvious when moving around you and using her muscles or constricting. Due to the lung structure of a snake, I don't find this surprising at all.
I have no qualms or concerns about either of them. As I said, they are fit and healthy, have never had RI. Possibly this whistling or wheezing noise is to do with the nasal structure internally. A slight bump the wrong way, interior of the nasal passages, could cause whistling or wheezing when breathing.
Just keep an eye on your snake and see if you can pin it down to a time or activity.
