I was going to suggest what hypnoctopus did, perhaps shedding related. How long have you had your snake? The reason I ask, is are you sure it's not a respiratory infection or similar? How do you know it's a few times in 24 hours? Meaning, most people don't have the luxury of sitting non stop with our snakes. Factor 5-8 hours of sleep, and work and/or school, and you in theory have now potentially decreased that "snake time" by 50-75%. This could mean this sound is more frequent than 2-3 time in 24 hours.
If it is a new snake, perhaps it is a guarded response to its new environment.
-braingarble