Expiration date for downloads

I was just notified by someone who made a digital purchase on my web site earlier this week that when she attempted to download the file today, she received a message that said the time had expired to download it. As a result, I had to send her the file through e-mail. I have EDD set so there is no limit on downloads, so why would she receive an expiration message? Is there another setting I need to configure? Thank you.