2013 SE @65000 miles

These cars are so darned quirky. A few years ago I went into my garage early morning and found all the interior lights on --- no explanation, somehow they "ignited" on their own overnight. My car's latest trick: All of the doors (including hatch) locked themselves overright, while the key was IN the car (no, not in the ignition, not anywhere near ANYthing). I always pull into the garage and leave the key fob in the car (if you knew where I live you'd know it isn't a significant security risk, and the garage is locked anyway). I never lock the car. How did the car lock itself with the key INSIDE (yes, there's a spare fob, but it was nowhere near, and not a possible conspirator)? I didn't push do anything when I exited the car (I've had the same routine for years. Didn't push any buttons or touch any door handles or anything at all. The key/fob had no way of coming into contact with anything or being "summoned" by anything. Has this happened to anyone else here? dab of research talked about battery issues--battery showed 3 volts and no weirdness/corrosion.