This minor "sneezing" is actually fairly common. Personally, I think its related to bedding. There is almost no research on the subject, but I think snakes can become allergic to things like wood shavings. I've also had snakes that did it just to express minor annoyance at being handled.
Try newspaper for awhile. Its actually one of the best substrates available. Its adsorbent, can fit any size enclosure, easilly replaced when soiled, and best of all its pradtcally free. Manny medium and large snakes will use it as an all-purpose hide, and it can be shredded to make an excellent fluffy bedding for small snakes.
RI symptoms include: frequent, loud sneezes; mucousy discharge, often forming bubbles; mouth held partly open for prolonged periods; head elevated; diffyculty breathing and gasping; poor muscle tone and listlessness; poor appetite/regurge; and the snake may spend an unusual amout of time basking.
If you really think your snake has an RI, take it to the vet ASAP. Most RIs are treatable, but the longer you wait the harder it can get.
Good Luck,
John D
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I am so not lesdysxic!
0.1 Creamsicle Cornsake "Yolanda"
1.0 Bairds Ratsnake "Steely Dan"
0.1 Desert Kingsnake "FATTY"
0.1 Black Rat (WV Rescue) "Roberta"