There was one time I noticed one of my BPs make a sneeze-like sound. She had spilled her water and there was a lot of condensation inside the tub, and in the process of taking her out, one of the drops of water landed right on her nose and went in her nostrils. She did not make the sneeze sound right away, but after I'd cleaned/dried the tub and put her away, a sound that really sounded very much like a sneeze came from her general direction.

Was it really a sneeze? I don't know. I can't even be 100% sure it was her that made the sound. Maybe it was more of a snort than a true sneeze. But I believe it was her and it was related to the water that got in her nose.

If your snake makes sounds like that with any consistency, I would be concerned about an RI, as others have already mentioned.