I have never personally dealt with an RI, and would like to hear input from someone who has, but that sounds like it could be something significant. I would also note that sometimes they can make strange noises. Especially during the shed cycle, or soon after due to stuck shed - presumably on the face/nostrils. This can create a strange sound when they breathe.
Also, are you 100% sure the python isn't hissing at you? Sounds like a deliberate exhale. Not like Sssssss.