Travel etiquette in plane

Today, I was traveling from IXD to DEL and this middle aged woman, couple of f rows ahead of me, put her legs up and was massaging her feet with the cold water bottle given by AI. Her legs were up for almost 2-3 mins before the air hostess came and asked her to put her legs down. The last was annoyed that she had to stop massaging her legs. How can she do that. How can one be oblivious to travel etiquette? And how can it be taught? Will a placard titled “ Airplane Etiquette “ help, if placed along with other literature? What are your thoughts. Note: On one hand I was surprised at her behavior but was pleasantly surprised at her body flexibility, given her age.