Pre-op transwoman who has yet to start crossdressing

Today was just a normal day at work( i work in retailing ) and a family entered the store, i was just smiling there and standing behind them, being ready to serve them if needed. They had a little girl around the age of 5-7. She asked her mom, is that a girl or a boy. At that moment, time seemed to have paused. I was dumbfounded, i'm not sure how to react, should i walk away? or continue standing there and be judged.

I am a pre-op transwoman. I have yet to start cross dressing, i did not put on make up, i dressed as a male. I only had a hairstyle longer than average males, approximately reaching my shoulders. Her mom answered after a second glance,'' he is a boy ''. I had a silent sigh of relief, even though i should be happy that i could pass at first glance as a girl even without dressing/makeup/surg. After they left, i was wondering, what has the world became, there's even a gender restriction for hair now ?

So have parents/schools/media been teaching children that boys must have short hair and girl must have long hair?

[Singapore]