Should I say something?

This guy used to always ignore me at parties, but when he saw me at a friend's wedding, he stepped out of the queue and began staring at me. A couple of minutes later, he sees me again and starts staring as I eat and doesn't look away even when I catch him. Another day, he heard someone talk and he casually glanced over to see who it was, but when he saw it was me, he basically turns his body around and just stands there staring while smiling at me. He doesn't come and talk either, so it's pretty much just awkward, I'm 21, he's 19.
Should I say something?
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