Let it go. She was trying to be nice. Would it help you to recognise that it was and act of a stranger, being kind to you, and your child, though admittedly this act took a form that you wouldn't have chosen?
It's a nice thing in the world when strangers take the time to be kind to people they don't know/us.
I can see that you wouldn't have chosen that particular action, but you seem so cross, that it seems to me you have chosen to interpret this as, almost, a randome act of unkindness, even assault.
The world is going to seem far more hostile than it really is if you choose to interpret actions of others this way. My suggestion would be to look at it as a well-intentioned act, one of generosity. Goodness knows, there are going to be enough times when people do act in genuinely hostile/alarming ways to you and yours.
Well - this is a well-hippy post, so, I might as well get hung for the whole sheep -- My advice would be to pass it on. Do something randomly nice for some stranger today. I've never read that book that suggests this (though I almost gatecrashed a party for the author once, some years ago). Even to my ears, it sounded a bit sickly. But, hey, the sun is shining, and it's probably ergonomically better for society as a whole to do nice things, rather than nasty things to unknown others.