I pissed off an instructor

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This class is a smaller sized lecture hall, about 80-90 people. I recently started bringing my laptop to class because most of the class is bringing theirs. I've seen several people with headphones in flat out watching Netflix during his lecture, and he had never said anything.
Usually I would work on an assignment from another class, because his lectures are extremely slow and it's hard for me to just focus on what he's saying without me doing something else in the background. Yesterday I didn't have anything to do so I was just on my laptop (in the very back, with sound muted), just on the web browser.

He then stops the entire lecture, walks over to me and slams my laptop down and then got in my face and told me to leave if I wanted to watch videos in his class and that he doesn't want me there. I don't know why he thought I was watching a video, but I guess it doesn't really matter.
About 5 minutes after he started his lecture back, he was transitioning to a new topic of his lecture and he asks if everybody understood the material he covered. He then points at me and says I obviously don't because I was watching a video.

Since the class was pretty large, I've heard random people talking about it around campus. I ended up sending him an email apologizing for disrespecting him and that it wasn't my intention, but I am afraid he is going to fuck with my grades now. The weird thing is that he didn't make the other 30-40 people put up their laptops.

I don't know if I need to do anything. Should I be worried about him targeting me?