By default, the headlights turn off 30 seconds after the ignition is switched off AND all doors are closed. I don't think the manual mentions that last part.
If, for example, you turn the car off, get out, close the door and then walk around to the back and open the rear door and leave it open while you unload your groceries, the lights will stay on until 30 seconds after you close the rear door. If it takes you five minutes to unload, the lights will stay on the entire time, as long as a door is open.
Does this explain what you've noticed? If you're saying that the lights run for several minutes even though all doors are closed, that isn't normal.