Being mistaken?

"Oops! Sorry!", Gilbert suddenly told Rachael. Racheal was quite shocked that he could ever talked to her. But what does he mean by "sorry"? She didn't even understand. Looking puzzled, she stared blankly at Gilbert.
Gilbert had been her classmate since their second year in high school. However, Gilbert never got along with anyone in the class. He, as well, never listen in class. All he would do is - sleeping. Don't get it? Gilbert was a teacher's son. A well-known one. He too, probably got proud of it and never look up to a teacher before. Not even once. Not even a second. When this happened, he never talked much to anyone in the class. Hardly.
Kenneth, who was listening to the whole conversation, got puzzled and asked Gilbert directly. "What do you mean?"
"Erm, you are Rachael or Hannah?"he asked Rachael. Once again, Rachael was puzzled. As she was about to answer his question, Kenneth blurted, "Rachael, of course."
"Oops! Just now the teacher blamed me on throwing her bag out of the class."
It was an incident happened earlier. Not very long. Around twenty minutes ago. Hannah and her friends had grudges with the teacher few days ago. They just didn't like the teacher, though the teacher just came to teach them for few days. Not even a week. However, somehow, they didn't like her. When the teacher went out to look for some exercise to be done by their class, they took the advantage to throw the teacher's bag out of the class.
"Then?" Kenneth and Rachael asked together.
"I thought you're Hannah. So, i told the teacher it's Rachael who did it."
"What?" Kenneth shouted. However, Rachael didn't give any response.
"So? How? Aiya~ I have to tell the teacher later. Sorry, Rachael."
"Nevermind. I don't really mind."
"You better go tell the teacher", Kenneth told Gilbert as if they were having a serious talk about it.
"Oh, okay. I'll go tell the teacher later."
They were actually waiting for an exam to be going on as they have their conversation. After their exam, "Eh, Rachael!" Gilbert called out onto her.
"Yes?"
"I already told the teacher that it's not you. Don't worry!"
Still, Rachael gave no reaction. She actually didn't mind it at all. She was just the member of the class. It's no big deal for her to take up the wrong-did. However, Hannah was their class' representative, what would happen if the teacher took the advantage to blame everything on her?