You are looking at this all wrong. You're goal should be to try and get this to happen more often. Every time it happens you should think of it as a compliment. Identify the ways you could anticipate anything else should could ask you to do and have it completed before she asks. Think of things she doesn't know she wants done if you have time and do them. My wife's work is a state of flux at the moment, every one is very tense and there aren't enough hours in the day. On a good day she gets to tell sales, the vice president and the president that she already though of that and took care of it. Your boss has problems of her own and only so much bandwidth to keep track of what you are doing. It's taken care of is the best response you can have to her concerns.