Athiests: What do you think of this miracle that God did for my mom?

When she was little, she wasn't a Christian, and she made failing grades. She was about to flunk the year of school. She had not studied, and knew she would fail the final test. She decided she would flip a coin, and pray that God would control the coin, and give her heads for true and tails for false. She did so, and was the first to finish, and took her paper to the front. The teacher immediately graded it, and called her out, and asked her to explain how she had gotten every answer wrong (it was around 50 questions, all of them true or false). Surprisingly, the teachers didn't make her flunk the year. But she realized that not only did God exist, but he wasn't pleased with her, and he made the coin move against her as a way of saying so. This is a true story. My mom is still alive, she's a Christian now, and she's very prophetic to this day, everything God says to her comes to pass. What do you think of this miracle?