Rehearsal is about more than learning notes and roadmap. It’s also, sometimes, about practicing performing.
The rumbling noises were either the drummer’s son barnstorming us in his Air Force jets or a thunderstorm. We determined which when the lights went out in the middle of my solo on “Now’s the Time”.
The bass dropped to half volume and the piano went silent. Immediately the drummer shifted to hi-hat and I started outlining chords while the bass kept walkin’. After a few moments the power came back on and we picked it back up.
These things happen.