Here in australia, you can take any photo in public place and dont really need to ask permission(little careful about kids). but some people get grouchy but most of them dont mind. Here I didnt ask and usually I dont ask permission because when you tell them that you are taking a pic, they try to smile. I like taking candid portraits.Wilma from the Flintstones, .
Btw, just curious....... did you ask for her permission before taking the photo?