No you are not being sensitive if I were in your shoes I would also felt upset
Ignore them. Don't let that make you down.
Some kids need attention by doing weird thing.
Same thing happened to me, got paper thrown at my head and heard laughter behind me. but when I turned around they acted like nothing was wrong .which was technically correct but I was stressed and threw it at his shoulder if that wasn't bad enough, i crush on him. He asked what was wrong the next day and I told him stressed.he said he was watching the office and a funny scene came up so that's why he laughed. Shit.
After class when I was walking home with my friends, I saw this one guy's reflection from a mirror, he was pretending to kick me off, then his group of friends laughed. That's not a direct bullying thobut still making me upset. I have tried to be neutral and not having problem with anyone tho. I'm just that classmate who's active in discussion. I cant believe even a plain potato like myself got a hater. I know I'm being too sensitive lol.