It it illegal to use the wrong address?

I volunteer at our local food pantry, it is run by a group of all the local churches and does on occasion receive some federal and state surplus food.
Our clients do not have to show proof of their income or lack there of, but they do have to show some kind of identification. We ask a few basic questions that are required because we do get a small amount of government assistance. One of the questions is their address. In order for us to serve them they must live in our area.
A few days ago I was working and a new client came in. I recognized the new person and knew where she lived several years ago, but also knew that she no longer lived there. (I know the people who live in that house now.) I was not the person who took her information.
After she left, I looked at her file and found that she had used her old address from several years ago. We had a copy of her drivers license and she was still using the old one with the now incorrect address. She had signed a form that says that all of the information that she had given us was true.
Is what she did illegal? and if so, what could be the consequences for her?
I live in the US.