I do some things automatically, out of habit. Take for example the action of leaving your house/apartment. I close the door, pick up my keys and lock the door. It all happens in one motion and as I have been walking away for a while I can grow uncertain wheter or not I actually locked the door. It was as if I took a conscious decision to close the door, but not to lock it. Locking it was merely an action integrated into the fact of closing the door.
The same thing applies to removing a pan from the stove. I can remember removing the pan, but did I shut off the stove? I have no memory of it. These things are also stressful to realize as leaving your house unlocked/stove on might have heavy repercussions.