I have the opposite experience as Orthodox Christian of seeing some un-churched people or visitor from foreign country not know what to do during Divine Service. Therefore, I speak to them after or even during to help them to feel more at home and to find out what is their religion or belief and to explain Orthodox belief to them.
It seems strange not to ask the person who could answer your question. This would make them feel at home in your Catolic church. I think in past that Americans are open people and willing to introduce themselve and start to converse. Perhaps computer has made Americans less willing to talk - sad - now you do not know why this person “backwards” crossing and standing