Schengen overstay [closed]

My Brazilian girlfriend left the Schengen area (Portugal) today to return to Brazil. It turned out she had overstayed by one day, something which she and I were responsible for, as we obviously were the ones to book her flights. She was taken aside and given a 40 Euro fine.

However, she was not notified of any possible later complications for returning to Schengen. As I am a Schengen citizen (Norway), we need to know if this could lead to any kind of trouble for her when she returns. Yes, it was obviously foolish not to make sure we were within the 90 days (my mistake, as I thought it was three months/93 days), but the accident has already happened.

By the way: Should she not have been denied entry in the first place, as her ticket was already suggesting she would overstay?