after some congested in-town driving (temp below 220), I could not start the car after turning it off for a couple of minutes. Turning the key would not engage the starter, but would start the electric fan, which would run as long as I kept the key turned. I raised the hood, waited five minutes or so, tried again, started normally. In 12 1/2 years, I've never had this happen before. What's the story?