I'm a college student--does my lab instructor like me?

I am 19 years old and he just turned 24. I’ve had a boyfriend that was about his age, so 24 isn’t that old of an age to me. My lab instructor is really attractive and I feel like we subtly flirt all the time in class. I added him on a social site and he accepted. The next lab class, he approaches me as he’s handing out papers, with a smile, and says: “Hey, we’re friends now”. Of course, I blushed! Every lab class, I feel like he’s sorta checking me out, like sometimes, I’ll look around the room, and then his eyes will be on me. One time, when I was asking him a question, he demonstrated it by touching my forearm lightly, and “showing” me that way, I guess. We’ve also talked about things, not related to the class, such as my Brazilian heritage and stuff. But I feel like he smiles at me a lot, and even when I’m talking to my classmates about something and he’s sorta eavesdropping, I see him smile outta the corner of his eye. What does this mean? He also kinda hints that if I want to stay after and look at some of the lab stuff, such as the bones and muscles (I’m in anatomy and physiology class) that I can anytime. We talk every now and then, as if were friends, instead of a teacher to student relationship. But I dunno. I added him into a a social site group, because I lost a lot of numbers, and so I added all my friends, and he rejected it =( So, I really don’t know if he’s at least somewhat interested or attracted to me. His actions seem like he is, but I don’t know if it’s just because he is friendly. He also smiles at me and makes eye contact with me a lot. I have a feeling he’s at least attracted to me. What do you guys think?