Here is what I have figured out: It seems to be a feature of the "User List."

I click on "User List." Then on "Last Online." The registered users currently online will have a yellow gremlin next to their name. When I click the first time, I usually get a mixture of white and yellow gremlins. So then I DOUBLE-CLICK again on "Last Online" and it sorts to show ALL the yellow gremlins at the top of the list. All the other gremlins below that are white.