OP - What does your rate say? What happened to someone else someplace else is irrelevant to what you agreed to.

Just compare what it will cost to check out early with what it will cost to simply pay for the night and pick the cheaper alternative.

Even if there is a fee, it may not be much. If the property is suddenly in need of the room, it may even waive the fee to get you out if you can agree to leave by a certain time.