Interesting story. It could be that she's just imitating you or her mother and doesn't know for sure what to do. Little kids are very good at imitating others, but sometimes, their timing doesn't work out so well.

As far as any concern that your daughter might be "screwing with you", well...

One day I was with my two kids at home while my wife was in training. I was preparing my kids for an outing and there was something that I had put on the floor (without really thinking it through), and I didn't want them to step on it.

"Don't step on that."

They stepped on it. Both of them. This is consistent with what a friend of mine told me long ago:

"The brain doesn't really understand words like 'no' and 'don't'. It only hears the other words."

Kids are particularly vulnerable this aspect of cognition, and generally, their life depends on cooperation. So I don't assume that they're messing with my head when I'm feeling annoyed by their behavior.

But once I feel that kind of a feeling, I try and figure out what I can change in me before I try to change them. I tend to have better outcomes that way.