Do you think my friend likes me?

Yesterday were walking with my other friend, basically were like a trio of close friends. So were walking either side of my friend and she says that her best friend who i know, keeps saying im her boyfriend. Were 17 btw, her friend keeps saying she's sure were going to go out. Anyway so after she says this we kind of both laugh it off and then she comes over to me smiling and starts holding onto my arm. Literally straight after because we were walking either side of my friend and she physically came over to me all smiling and started holding my arm, i just kept walking and didn't really smile back not sure why though. Then she let go after a while could this mean anything? Why would her friend think were going out? Were close friends but that's it, there's nothing to show her friend that im her boyfriend. Maybe her friend thinks she likes me, if she did though how often is it that the best friend of a girl is wrong anyway. Also why did she come over to me straight after and hold my arm? She always seems to do this all the time, but doesn't do it to my other friend.