I sent a note to the interviewer, thanking him for his time (totally lost track of it over a very busy weekend), and within 15 minutes, got an email to schedule the next step.

Coincidence? Probably. But that doesn't make me less happy to have reached back anyway -- this process sucks on both sides of the table. If there's anything I can do to make it easier for them, I'm happy to do it as a human, but also because it may help me.

Now I just gotta prepare for a "live analysis/logic session." Let the anxiety (re)commence!