But how did she know it was your birthday? Is she some crazy stalker lady or do they require some official ID at Pokemon centers? This raises questions.
I think that started way back in gen 4 (Since the DS could track the date and you had the option to store your birthday in your DS profile also in gen 4 certain days (Christmas eve for example) you get a diamond dust effect in certain routes (diamond dust wasn't hail so no weather effects were there)