A guy grabbed my boob on two separate occasions during a lift in dance class, was it purposeful or just an accident?

There's a guy in dance class who is good all around guy. He is great at dancing and friendly, someone you'd want to trust. Though recently during our some of our classes and incident happened. The first time we were doing a bridal spin and he had his hand placed on the side of my boob but I didn't mention it cause it seemed like a innocent accident. This second time though he was spinning me and his hand was fully gripping my boob. I put my hand on his to try to make him move but he didn't budge. I have fairly small boobs but I don't understand how he couldn't have realized he was groping me for nearly 30 seconds. After the lift was done he acted completely normal and didn't acknowledge what happened at all. It made me feel extremely uncomfortable. If it was any other guy I would assume he was a creep but I feel this guy is genuinely good person. Do you think he just didn't notice what happened or is not as much of a respectful guy as I thought? And how do I approach him about something like this, if at all?

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Thank you all for your feedback. Some suggest I press charges but I'm I can't bring myself to go that far, especially if it's nothing serious. If anything close to dangerous territory happens again then I plan on confronting him directly and talking to a teacher/councilor. I also wanted to clarify that we are both minors close in age as there seemed to be confusion.
A guy grabbed my boob on two separate occasions during a lift in dance class, was it purposeful or just an accident?
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