Meditation is like a single log of wood. Insight and investigation are one end of the log; calm and concentration are the other end. If you lift up the whole log, both sides come up at once. Which is concentration and which is insight? Just this mind.
I probably would've kept slogging on that same chord change, because there's a tendency to have that happen. You get into the cadence in your mind, and it's hard to make the kind of left turn that you probably need to keep it really interesting.