Do tubes heal themselves?

Had a flat on Thursday on the way home from work. It was cold and very windy, and I was only 1.5 miles from home. I decided I'd just walk the bike the rest of the way home and deal with the flat in my garage rather than freeze while I was trying to fix it on the side of the road.

When I got home we were in a hurry to leave town for a couple days. For some reason I decided to pump up the tire before we left. I figured I'd fix the flat when we returned on Sunday.

Yesterday afternoon my tire was still fully pressurized. So I didn't mess with it. Was still inflated this morning, so I just went ahead and rode to work. Didn't lose any air on my commute this morning.

Weird.