Could be your snake just drank some water or there is a possibility of respiratory infection. Increase temps slightly and WATCH VERY CAREFULLY for any other signs. If you can see inside his mouth check for stringy discharge, or if he makes any kind of noises that may resemble difficulty breathing. Do not take chances if signs continue, take it to a qualified vet. RI's can be dangerous, especially for colubrids. Hope this helps.
:I just reacently noticed my snake blow two bubbles. Does anybody know what could be wrong?