Is it normal that he stares at me like this?

Before I get into my story, here's some info. I'm an 18 year old gay guy(out). I'm not very effeminate nor flamboyant and most people have to ask to find out. There is this guy I know. His name is Daniel(story sake). He's a really good friend of mine and he is straight. I noticed that he has a habit of looking at me in a strange way. He'll gaze straight into my eyes with this mischievous, child like, eyes smiling stare. He ALWAYS does this to me. He even goes as far as to get my attention non verbally in a secretive sort of way. He'll look at me til I look back at him. Me being kind of shy, I'll ignore him til I can't help but look back. When I do look at him he smiles though It's a weird smile. It's almost a weird kind of sensual smile as of he wants something. At first I thought he just did that to everyone. (He was in my math class at my community college and sat right across from me.) There were two girls sitting at the table we were at as well(very attractive girls too) I noticed he wouldn't stare at them the same way. In fact, he doesn't look at anyone like that. I have no idea why he does and he started after we first met and really clicked. He laughs at all my jokes and I his. He actually understands my view points and even understands my being a slight masochist.(he also seemed to really like that) It's just weird because he'd do it all class period and it was difficult to concentrate. I'm not sure what is up with him. It doesn't bother me other then making me nervous and making my stomach flutter(which is very rare)
I do find him to be very attractive. He also has the 2nd most beautiful eyes I've ever seen. Why would he stare at me like that? Should I be alarmed? What would you guys/gals do?