I got out of my Max leaving the keys in the ignition with the engine running. > did close the door. It seams it locked itself.
Is this supposed to happen? Can you not leave the car with the motor running?

 

If the key is in the ignition and the engine is running, the doors will not lock if a door is open. I have tried this before. For example, I leave the engine running. A passenger opens the door. While the door is open, the car will not lock using the power locks. What you described.... never tried it.

 

During one of the bigger (first) snow storms we got here in NYC the same thing happened to me. Typically, as I do whenever it snows, I start the car first so it can warm up and help loosen up the snow/ice as I'm cleaning off the car. Of course I close the door so that no snow or ice gets inside the car. Well after about 30 minutes of cleaning the car (since we had gotten over a foot) to my surprise the doors were locked! I couldn't believe it...I had to walk all the way back to my house in a blizzard and THANKFULLY had taken the second remote out of the car (had just picked up the car that weekend!) Since that incident I have not tried to replicate that situation as I wouldn't want to be in that situation again!

 

That doesn't sound like the default behavior for the factory entry system.

 

This happened to me twice. I thought something was wrong with my door locks. But you want to know why mine did this? Well, I found out that when I open the door, I sometimes would hit the lock mechanism on top of the door handle. When I would go and open the door, I would slightly, ever so slightly, hit it backwards triggering the lock mode and locking the door when I close the door. When I come back to the door, I would be locked out and have to call my parents to help me open it since they have the other pair. I solved this problem by unlocking ALL the doors when I get into the car, that way when the I accidentally hit the door lock mechanism when I open the door, just the drivers side would be locked and I can get in one of the passenger side.

Problem- Poor door location lock mechanism

If you don't have any clue what door lock mechanism I am talking about, I'll describe it to you. Its the one where you can push or pull it forward to lock or unlock the door manually.