On the topic of, out of the blue, discussing your children's belief in Santa Clause with a stranger (me):
I (now) understand that culturally this was used as an indicator of the maturity of the children, and that this interaction is, culturally, normal.
But as an outsider, it's kinda weird, right?
There was obviously sub-communication behind the statement that I missed. She was using body language to convey her meaning, and I was a blind man unable to see.
To someone who picked up the intended meaning, it would be normal, but without that, it's objectively weird, right?
"My child believes that a mythical figure is real" is not something I would expect to learn after knowing someone for less than 2 hours.
1/