So, the first rule of bicycle flat repair is always check the tire to make sure that whatever may have caused the first flat is out of the tire.
When I got to Walnut Creek today and I was riding down the ramp to cross the street, the bike fishtailed a bit. It did this in a way that reminded me of hauling rock in dad's pickup truck my year at home between undergrad and grad school. I was hauling pea gravel a half-yard at a time to fill up the bed for the new hot tub my parents had bought. And half yard was about all that the truck could handle. When I took a turn, I could feel the center of the wheels slide out. It required very slow travel.
So I've jsut taken the rear bike wheel off again, and through careful feeling and flexing of the tire, I found a nice piece of glass that with pressure was poking a hole in the inner tube.
I guess I'll walk over to one of the downtown WC bike shops, and get me a new inner tube. Maybe a couple. And a patch kit.