puffy throat in Eastern Indigo

Has anyone else observed Eastern indigo with a puffy throat while being handled? Like a pouch under it's chin. My big male does this especially, and my smaller female to a lesser degree. It's not the neck extension and rearing back posture that they engage when agitated/excited. I wonder if this is common or if it's a sign of illness? Mine are robust and eat like horses and seem very healthy. Any comments?

It is normal for indigos. Just a threat display.

Thanks Tim!

+1.....handle them more, and the threat will stop. These snakes get to love being handled: after handling mine, maybe taking them outside for a while, they will always come to the front of the cage, even crawl out into my hands, for more!

I kid you not. I've had many thousands of snakes in my life, but only Drymarchon responds like this to handling. They are scared of nothing, and absolutely come to know their owners. The more they are handled, the happier they will be.