Hi Tim,
First, welcome to thamnophis.com
. I hope you like it here and find plenty of help. Now, If the huffing sound isn't continuous, then I don't think it's an issue. I've noticed that after I've let mine swim too long, they sometimes have a "clicking" sound when they breathe for several minutes afterward. I've also noticed that new snakes will sometimes "click" or even make a sneezing sound while they're adjusting. This is a defensive behavior, and they stop doing it after they calm down. Does this sound like what you're experiencing, or do you notice something else?
Two more questions: How long have you had the snake, and how long has it been doing this?
Rick