Do you think he's turned off, or thinks i'm stupid?

There was this really hot guy who added me on facebook who goes to my school and he's a year older than me. (i'm in grade ten he's in grade 11). So he would wave to me if I walked by his classroom and I would just smile and wave. One day I was with my friends and he told me to come here and smiled at me and I was a bit nervous but I went and he was like hey (my name) how are you (we'll call him bob) my name is bob and he put his hand out. I just stared at his hand for a minute and got confused because I usually shake with my right hand but since we're both right handed I had to use my left hand. I smiled and introduced myself even though he just said my name, and then he and his friend looked at each other and laughed and I awkwardly walked away. They didn't laugh in a mean way thought but I was so embarrassed.