Weird update:

the "bang" mentioned in my first post may not have been the shock. since that happened, I've heard 2 more bangs on the same trail, in very similar spots. I smelled gunpowder one of the times. I think some punk kids have been putting some kind of fireworks out there-- snap pops, pull fireworks, or something. I actually looked for a firework the most recent time, today, but couldn't find anything.

the shock, however, had definitely lost all damping. I'm calling tomorrow to check the status on it... hopefully it is repaired and coming back soon!