Hi ! long time lurker first time poster

what happened:

i was walking in a mall with my friends ( 1m/1f) and they decided to go the washroom.

i then stood outside the walkway and just looked around as it was my first ever visit to the mall.

when looking around, i locked eyes once with this girl who was with 2 other older lady (i assume mum/aunt). she was sitting at a table with them having coffee and chatting.

i then continued looking around as i really just wanted to see the mall , and i turned around and we locked eyes AGAIN.

this time, i smiled at her, I smiled because it was a task/challenge i gave myself

and she smiled BACK - pretty sure its directed as me as i was the only one at that line of sight.

so...should i have just approached?

or is she just smiling cause its was awkward? or just being courteous?

honestly i am ok that i missed the opportunity but i am just curious about what it means?

thanks !