Auntie/Uncle shouldn't be used for your non-related friends

I would consider that a compliment. You could talk to her if it bothers you, but be prepared because she might be offended.

You can never have enough aunts and uncles in your life, whether by blood or not.

Take it as a compliment.

When I was a kid it wasn't at all unusual for mothers (always seemed to be mothers for some reason), when talking to their kids, to refer to another child's mother who was coming over as 'Your auntie (insert name) is popping round'. I never understood it. My wife and I never did it with our kids.

My parents used to do it. It used to be quite a common thing to do in my neck of the woods. Looking back on it, I think it was supposed to signal 'trusted adult'.

Why would you have a problem with it? I'm auntie to quite a few kids that aren't my siblings'.

It's normal in non western countries to call anyone older than you auntie or uncle. It was always common in Britain until around this century too. I always called my god parents auntie and uncle even though they weren't related.

i have four nieces/nephews and the only one that calls me uncle is the oldest one. i babysat him a lot as a kid.

I called all my parent's friends Aunt or Uncle when I was little. It's not a big deal.