The last time I had to fix a flat, it took me more time to find the culprit (a piece of wire from a steel belted radial) than it did to swap out the tube and put everything back on.

It's always worth spending the time to find out what caused the flat especially if it isn't obvious.

This thread also reminds me that I should get a mini pump for backup because those presta valves can be a little tricky.