I figure my four flat tires were just a run of bad luck. I could have caused my own bad luck with thin and worn tires. I had some inexpensive Performance Forte Strada K tires I got on sale for $12. Yeah, I know you get what you pay for but I got over 2,500 miles out of them. I guess I should have changed tires at 2,400 miles. I have Michelins on now.
Everyone I rode with was supportive and patient. No one complained. We were running out of 25mm tubes, though. The good thing is that I got a lot of practice changing tires. Sunday morning when I was fixing the fourth flat I discovered an easier way to do it. One of those "doh! moments": why didn't I think of this before?