Which is what you do next. After thanking her, ask her to walk you through her thought process, explaining that the next time something similar occurs, you want to be in a position to handle it so she doesn't have to jump in.
One more possibility: From here on in, the moment anything comes up that gives you even a whiff of the possibility she'll be likely to jump in, get the jump on her instead. Knock on her door, explain the situation, and tell her you'd like to run by her how you plan to handle it to see if she thinks you're taking the right approach.
Not only micromanagers but all managers need to develop trust in their employees so that they know how much or how little supervision is needed to make sure work is handled properly.
Micromanagers just don't know how to develop it. So it's up to you to guide them through the process.