Feeling guilty after delaying a beautiful woman from getting coffee

I usually get into work about 9:30. I then go and but a cup of coffee at the cafe near my office. Today the student in front of me was wearing a smart brown rain coat. She had blond hair and was beautiful in a normal practical way. She went to the first coffee machine. I went to the next one along. I was just getting the paper cup ready to receive the dark coffee. Somehow there was a problem with her machine and she turned to use mine. It was a split second thing, but I feel that if I was a gentleman I would have let her use mine. She was a child off the light, so there was no question of a small  act of generosity starting a conversation leading to a relationship of some kind. I Just feel I was being selfish. Perhaps I can blame my caffeine addiction.