Playing second of 2 nights at a dive bar last night. I noticed a small spring on the floor of the stage, then what looked like a nail. On set break I picked both up and thought "that looks like a bridge saddle adjustment screw for a bass." Turns out it had worked itself out of my bass and the 1st saddle was being held in place by the string pressure. It could have fallen out the night before, I didn't notice. I quickly reinstalled the screw and spring and the p-bass still in-tune. Normally I'm not that observant, just dumb luck.