Playing with her hair while talking is one subconscious way of
nervousness. If u study body language, its just some thing that we
do subconsciously without knowing. Its either she is interested in
u, or trying to catch your attention. Try to see if she looks into
ur eyes. Usually if a girl likes u, she will take galnces at u but
indirectly. Afraid to have direct contact with u. Take note of the
way her feet is pointing. If her feet is pointing towards u means
she is interested in talking to u. Of course get hints from the way
she speaks too. 
