From where did you read this from? My clownfish do the exact same thing for the past week. And I'd like to know more about this. I have seen them "cleaning" that certain spot next to their anemone.
By the way, aquareeferman, thank you so much for this info even though this isn't even my thread. I have been wondering for so long why my pair has been doing this, and this reason seems most likely. How long does this dominance sex-change take? Mine have been doing it very vigourously for the past two days since I moved a rock covering where they were cleaning.