Teaching or Terrifying?

Tonight I was out late at a school function. My daughters and I stopped to pick up dinner for my husband. The parking lot was very dark. I told them to quickly get in the car and I locked the doors. I unwittingly scared them. I was just trying to avoid giving any opportunist an opening. I did check out my surroundings, but I was still unsure, because the parking lot was so dark. My question is, "Did I teach my girls a good lesson or did I needlessly frighten them?"