I think the most salient feature of this story is that it is a ghost story. Not just that, it is a ghost story being told around a camp fire. It is also a future ghost story that uses ruins from a mysterious past which seems a lot like our present. In these ruins a "cursed object" is found: a cell phone. This phone has to be, if not cursed, at least supernatural in some way; otherwise it is hard to explain how a portable phone could still be in working order after being buried in the ground for 800 years or more. Even its battery still has a charge!
Jonathan Laidlow seems convinced that the sounds of "something, an animal or something, moving around in the dark" that occur when Dik started tapping two sticks together "trying to get the noise right" were the sounds of the being that brought the powder to Jo An rising up. I am equally convinced it was just an ordinary animal, or the wind, and the timing was a coincidence. After all, there are no mysterious movements in the underbrush when several people are banging sticks earlier, before they all had heard the story. Wolfe is just emphasizing that Dik and the others were genuinely scared by Jak's story. It's also slightly humorous, since Dik obviously scared himself.