Most Helpful Girl
be polite and thank her for wishing you happy birthday. if you don't mind talking to her and if you would like for you two to catch up, you can ask her how her life is going or something like that. i don't know if you had nasty breakup or not, but maybe she wasn't ready to hear from you for a long time. maybe now she wants to stay on good terms with you or maybe that could be a rebound call or even a 'let's have sex' call. it's rude to say, but i called my exes after a long time only if i needed sex. maybe it's not her case. but anyway if it bothers you, try to be nice and see where the conversation is going. that's the only way to find our her reasons for contacting you again. good luck!