Hah! I had to stop for groceries. The miles sure did fly by. We met a rider on a fixed gear Ibis Scorcher, one of 100 made, shown here:
Solveg said just what I was thinking: when riding socially with someone else, you're not worried about speed, cadence, tire pressure, hill climbs, or whatever. I now will have a bit more tolerance when I approach others riding side by side, reluctant to drop into single file.
Karl