Just the opposite happened to me. I was flying on an evening flight from Chicago to Houston on Continental Airlines, and the flight was delayed and we arrived at IAH at about 11 PM. We pulled up to the empty gate, and the baggage crew removed the baggage but no one was working the jetway. The pilot several times said he was trying to contact someone at the airport, but they told him all of the Continental gate agents had gone home.
Finally, after two hours someone operated the jetway, and we departed the aircraft at 1 AM.