He may be testing the waters; trying to catch your reactions to it. Could also be that he is comfortable around you too. Its easily 50-50 as to what his thoughts were, and even less odds as to why he did so. If I were to get to the point where my confidence allowed me to touch a girl, or even her shoulder for that fact, yes, I would to some degree definitely like her. Could also be because I'm pretty shy in most regards, so simply touching a girl is a huge task for me; almost as tasking as trying to approach a girl.
Unless his body language said otherwise or he acts this way all the time, I'd say its a fairly decent chance he might.
Do you mean if he touches you just one time? Now if he keeps finding reasons to touch you, then I would say that he most likely does have feelings for you. Unless he is like that with other people all the time. He might just be a touchy feely person compared to most people.