So What Does This Behavior Mean?

Surprise, surprise, it's Gambit that's stumped me yet again. Last night he was startled by one of my neighbors outside after dark. Instead of barking or growling, which is his usual MO, he pulled a new one.

He gaped his mouth open really wide, which he's done before. It's a normal coyote defensive maneuver. But this time he started breathing really hard. Not in a stressed way, but really forceful puffs of air. It was so forceful that it almost sounded like he was going 'Ha! Ha! Ha!" It was honestly a little spooky.

He stopped when I pointed and told him to go home. I've never heard him do that before.

Thoughts?

Some cats hiss in a similar fashion - short puffs of air rather than a long stream. Maybe it's a coyote equivalent?

For some reason, I'm thinking he was smelling the air.

This sounds to me like he may have had the equivalent of doggie hiccups. Apparently its quite common.

That's what I was thinking, maybe some kind of threat display?