Linda and I arranged to meet her sister and brother-in-law today at the end of my ride. I left the car at the restaurant north of Burlington, and planned to ride a 15-mile loop route with a gradual hill in the middle. I had done the similar route with the hill two days ago in the opposite direction. The wind was blowing, and unless it's a tail wind, I don't like riding in the wind. I did the hill OK, and that pleasantly surprised me. I chose to shorten the route to make it back to lunch on time, but still wound up doing 13 miles.
While we were enjoying lunch in the beautiful weather, I left my bike on the rack and locked up. Linda took that car home and I drove the other car to the recycle center to drop off some stuff. When I got home and began to take the bike off the rack to store it for the night, I noticed that the rear tire was flat. I looked it over and could find no exterior damage. So, I got my goodies together and set about to change my first flat with this bike. I got the tire broken down, but could find no leak in the tube nor any nail or anything sharp sticking into the tire. I put the tire back together and pumped it up. I'm going to let it sit in the garage tonight and see if it is still holding pressure in the AM. I'm now suspecting that some wise guy let the air out of the tire while we were in the restaurant. What I've learned from this is 1. sit where I can keep an eye on my bike and trailer, and 2. pump up an unexpected flat first to see if the air was just let out. While I would rather have not had to break down the tire, the experience was good. I just hope I don't have to repeat it too often.