Weird, loud puff?

Today I was playing a video game and I heard a weird muffled sound come from my BP's tank. I stopped after the second time I heard it, and listened. It was just a loud, muffled-ish puff. I bent down to look at him, and when he did it again, it was like his whole body moved, like he was really forcefully exhaling or something. It's not a whistle, and I didn't see any mucus build up. It happened maybe six times total before he stopped, with maybe 1 minute intervals in between each puff. If this something to worry about? Is he okay? Are there problem signs I should watch out for for the next few days?

Maybe he got substrate in his nose and was trying to expel it?

I really don't think so. I can't see anything on his eyes or any part of his face..

UPDATE: He's still doing it, it's infrequent, but it's happening. It sounds sort of like a cough when you're sick and have mucus in your throat. Please help!! What can I do to help him? Is it RI? The symptoms aren't constant and he's not opening his mouth, stargazing, and there's no bubbles near his nose.

Also note: He only recently started doing this after I fed him this week. Does that have something to do with it?

Sounds like something needs to come out, and I would guess it's from the front end rather than the back end. May sound weird, but you might consider trying to smell your critter to see if anything seems septic in there. My initial guess would have been something in the nose as well, but if you say it sounds more like a mucus cough, I'd be a little more concerned and begin considering a visit to the vet.