At first I thought I had locked my keys in the truck. Then I realized that the truck was not supposed to lock when the key was in the ignition. The next day I, again, left the keys in the truck while visiting my family. The truck locked all by itself again. Since then, I have realized the truck will lock all by itself whether the keys are in the ignition, not in the ignition or while running at idle (in park position). Just started in the last week.