Maybe she sees more of what goes on in the organisation and knows what jobs others would rather avoid for whatever reason? For what it’s worth, when I was still at MIND we organised a mental health survey once, and it felt a bit of a slog getting everything into the envelopes to be sent off. That was with several people working together to do it!
And everyone’s perspective is different. What you do might be easy, but it still has value. Some of the tasks I do at work are easy but I’m thrilled when others do them for me, because it’s one less thing I have to worry about. There’s a chance she/organisation was genuinely grateful and felt this was a good way to thank you properly. I can totally sympathise with how you felt about being thrust into the spotlight, though, it can be uncomfortable even when you know it’s coming. It’s great that you can reflect on what happened, and want to clear the air over any misunderstandings.