same thing happened to me. a girl was following me, and then i started a convo with her, she seemed to ask questions back, cute little chick, and i asked her name before get her number... and she told me her name, and i like to guess where someone is from based on their name, and i realized she was jewish, and "oh you're jewish" and she started laughing or giggling somewhat as if she was surprised. i thought she was just messing me with me, i said why's that funny? and she mumbled something idk... then i ask for her number, and she said no social media only. i said i dont have social media, unless she wanted my reddit name, and she said "ok well then see you around". then she lingered a bit and i said thanks for her recommendation on something, and just left. but i think she's thinking why didn't i just give him my number, it's so much less personal than social media lol