I suspect this is related to the Belt-Minder feature and/or the Parking brake on chime. Key-in-ignition warning chime should only sound when the key is left in the ignition and the driver's door is open. Headlamps on warning chime should only sound when the lights are on, the ignition is off and the driver's door is opened. Parking brake chime should only sound when the brake is left on and the vehicle is driven. The owner's guide says to contact your authorized dealer as soon as possible if the warning chime stays on after the parking break is off, which it is.