I've noticed this feature this past week as well. It was meanwhile cancelled, due to your interference... It was just introduced last week. My thesis is that it was part of a new search tool, which shows the people you have searched for the most. (Meaning if you went to their pages through links they will not be included here). This change came with another change (which now disappeared together with this feature) - when you search for friends and type their name, the ones you typed most often in the past came up first, as opposed to alphabetically.