Yes, that's the recent change in the merc panel. The old Hire/Unlock/Return button (the $hire$ in the Fetish screenshot) is gone, replaced by the green handshake button at the bottom of the default screenshot (Hire or Unlock depending on whether the merc's unlocked or not) and the two buttons just below the active merc slot (Suspend and Return, if one can be used it lights up). From what I can tell there's no way to recreate the old 3-way functionality.
"Hey! I'm not illiterate. I had a book once. ...could've used some ketchup though..."