Mizzou, that does sound like the other mom definitely crossed a serious line! Yikes.
This reminded me of a completely different conversation I'd had a couple weeks back with another mom of a girl scout, she was asking about dd's grade, then age, then very specifically her birth month..I was really not sure what she was getting at (of course finding out exactly what dd is, I guess ??)
Anyway, I usually try to steer away from things like this by saying yeah, she's a bit young. This lady brought up the fact that she'd tried to move her own girl into k a bit early and had been told to 'give her the gift of time'. She sounded a bit cranky about the whole thing, but in the end I came away with the feeling she was more regretting a missed option rather than mad at me...
She continues to be friendly so I think she was just too curious, to my relief. But boy, that gift of time...whew!