[DanEC]

I would guess coil breaking down form heat or fuel perculating out of the carb bowls on shut down - but your car shouldn't get that heat soaked in a 3 mile drive. If you have a points distributor with an electronic ignition added on, that is another possibility.

Are you spending time in the coffee shop during which the car could cool a bit or are you picking up coffee and leaving immediately?

It's got to be either fuel or spark. Next time pull the air cleaner before re-starting and see if it squirts fuel when you manipulate the throttle. If it squirts fuel then test for spark with a plug or coil wire.