Aw, that's a great little moment! I'm glad you had it :-)

My mum still seems to muck around in heteronormativity. And kindly said the other day that I should probably expect to some day run into something unpleasant over my orientation + gender identity. I told her nicely I had, though so far mostly online. (And I haven't yet gone into the systemic things of devaluating my gender all the time. I mentioned it once and it was mostly like "you probably have to get used to that". My answer: I am. It's been 5 years of this for me. Doesn't mean it gets any less annoying or hurtful.)
That said, she IS against overt *isms and *phobias as well and she's supportive etc. etc. But yeah.

So yay for your mum getting it! Gives lots of hope and good feelings.