Through friends, extended family, books, TV and the experiences they have in their community, children absorb values and societal norms. And I happened to know for a fact that the only doctors Melissa had ever been to had been women. Yet every time she overheard a conversation about doctors, they were referred to as men. Every book she read about doctors showed men. I thought my doctor was a woman' was challenged by the greater authority of her aunt and the accumulated weight of images from world around her.
Children learn values through our explanations of the world.
We can't always control our child's environment. We may have chosen the grocery store, but we don't control all the people who are going to be in the grocery store. Our children sometimes witness or hear things we wish they hadn't seen or heard. But the fact that we are with them or that they can come home and tell us about it, gives us a chance to share our perspective on what happened. I think she was worried about your safety.