Is the user responsible for saving their files?

In a tech support session, a user was working when I arrived. I had an appointment to install and configure a video card for her pc. She said ok, go ahead and left the room. I shut down the pc, installed the card, started the pc and setup the card.
The user had left the room. She returns to scold me about not saving ‘her’ documents. I did not know I was responsible for her documents, or anythng beyond my actual work.