I haven’t owned my 2011 Subaru Outback long enough to offer any way this might have happened, but I will describe how this happened to me in my previous car.
I had a 1996 Toyota 4Runner and got the VIP Security System with it, dealer installed, and I assume it was “state of the art” in the dark ages of 1996.
This system had over a dozen complex “features” and one of them was a timeout lock. If you lock the doors, and let’s say while leaving the car you accidentally “bump” the unlock button, your car would be unsafe. This is actually quite common with ALL remotes even today. You can be hundreds of feet away, inside your home, and a kid can press a button, and BINGO, your car opens and you don’t know it! Now, your car stays unlocked all day, week, whatever! Bad thing.
A timeout feature says if a car has been locked and for some reason it is unlocked with the remote, if NO DOOR is opened within 15 or 20 seconds, it LOCKS ALL DOORS again. This is really a great feature and gives you a lot of peace of mind.
Years passed. More than a decade. One day, before I went for a run, I decided to “unload” my keys from my shorts as I went for a short run, so I put them on the floor of the passenger compartment of the car. I opened the locked car, put the keys under the floor and closed the door. As I started my run, I heard that awful “beep” sound of all the doors closing! In the end, I had to use the “emergency” house key I had hidden in that old car years ago, and I got into my locked house where I had a spare car key. That saved me a few hundred dollars for sure!
So what happened?
As my car got older, the little button that is on every door that says “I’m open” got stuck! This button does two things: it turns on the dome light and tells the security system “someone opened a door.” As I described earlier, any door that is opened DURING PASS TIMES tells the automatic recloser NOT to turn on. But since this switch was “stuck” it didn’t work and I knew it because the dome light would often not come on or come on after a minute or two when the switch would finally work.
Now I’m not saying this or anything like that happened to shut you out of your Subaru. But he explains a complicated way in which these technological “traps” can occur. I don’t think the Outback has a timeout feature either, but you got locked out and it has happened to a few people and it’s tricky because it doesn’t seem to be reproducible.
Study it further and I’ll bet you’ll eventually figure it out. And keep a spare key somewhere!