Do I deserve the grade?

Recently I sat a mock GCSE paper for biology. I received my result yesterday and got an A*. I feel guilty because the night before I did my third past paper I d done for revision. The paper I did was in the exam, I had no idea it was going to come up and I think I received the same grade when I first did the paper. I told one of my friends that s what happened and she blabbed to half of the class. Someone obviously was jealous and when the teacher asked them how they could improve next time they said, "I think I ll just do what Chloe did last time - do the paper before the exam." I found this really rude. The teacher said she d just pretended she hadn t heard that, not sure if she meant me or him though.