Perhaps she's at home, calmed down now and thought "Oh, why did he tell me that...and realized perhaps it wasn't so smart". But of course you always get the aggro and not the thanks ;)
You're right. I do it when I think it's worth mentioning and the reactions do vary, so I will carry on doing it. Even if someone's a bit rude, they might still think about it...
People nearly always get defensive alas...
...but better say it and then you've tried?
Perhaps she's at home, calmed down now and thought "Oh, why did he tell me that...and realized perhaps it wasn't so smart". But of course you always get the aggro and not the thanks ;)