Why does he stare at me this way?

I noticed one of classmates has been starring at me but he doesn’t say anything. He’s actually a tall, quiet, and macho guy with good physique who’s married in his 30s. But lately I noticed he will stare at me across the room or by some of my movements such as yesterday when all I did was turned my body to my right on my seat because I was thinking of getting up… he would looked over right away and it shook me where I felt awkward. It confuses me. The last time I said hi to him and told him he did a good job on his presentation. He responded but he doesn’t keep the engagement going. So it doesn’t make me feel like he stared because he wants to talk to me.
Why does he stare at me this way?
Post Opinion