simple as it is
you could either sit home and wait for her to call you all day, or you can move on feeling good that you met a very cute girl today on your way to work... chances that she is going to call are 50% - 50% in my opinion, but thats only me. maybe she didnt want to put you down so she took your card, maybe she wants to have second thoughts, or maybe she is really interested, you will never know till she calls you- or not. anyways, i appreciate you being spontaneous and random, and good luck !!!