This question is also intended to probe how well you accept criticism and direction.
BEST ANSWERS: Begin by emphasizing the extremely positive feedback you’ve gotten throughout your career and (if it’s true) that your performance reviews have been uniformly excellent.
Of course, no one is perfect and you always welcome suggestions on how to improve your performance. Then, give an example of a not-too-damaging learning experience from early in your career and relate the ways this lesson has since helped you. This demonstrates that you learned from the experience and the lesson is now one of the strongest breastplates in your suit of armor.
If you are pressed for a criticism from a recent position, choose something fairly trivial that in no way is essential to your successful performance. Add that you’ve learned from this, too, and over the past several years/months, it’s no longer an area of concern because you now make it a regular practice to…etc.
Another way to answer this question would be to describe your intention to broaden your master of an area of growing importance in your field. For example, this might be a computer program you’ve been meaning to sit down and learn… a new management technique you’ve read about…or perhaps attending a seminar on some cutting-edge branch of your profession.
Again, the key is to focus on something not essential to your brilliant performance but which adds yet another dimension to your already impressive knowledge base.