I'm happy for you that someone made a difference in your day! We had it happen to us a couple of times when DH was in uniform. When DH has to travel he tries to buy the meal of traveling military members he encounters. Often, someone has already beaten him to it!!

A local radio station has a program they call Be the Drive Thru Difference... the goal is to make the day of someone behind you in line at your fav drive thru joint.