I hate it when people finish my words for me. It's humiliating and embarrassing. Like I was struggling so much the person felt like they had to step in and help me. I find it to be extremely rude. Also, just because you didn't see her react negatively to it doesn't mean she was okay with it. I rarely say anything to people I've just met because I'm not confrontational, and already embarrassed from them doing it. I'd say air on the side of caution and let her get it out herself.