Latches/locks/linkage Related Problems of the 2009 Toyota Scion Xb

Latches/locks/linkage problem

I've owned two Scion Xbs (2008 & 2009). In extremely hot or cold weather the car doors occasionally lock themselves (either when the keys remain in the car floor or when I take them w/me when I get out). I've reported this to my Toyota dealer on both cars (when going after a key to unlock the car). Their response is to say such is impossible & they have never heard of any other complaints (I reminded the service rep this was my second visit to him). The latest incident occurred during my return from raleigh during a snow storm. Sixty miles from home I stopped to refuel. I exited the car leaving the keys in the ignition (w/engine off). Upon returning from paying for fuel the car was again locked. Not wanting to brake a window to gain access, I called my son to bring my extra key from home. Thankfully I had a warm gas station in which to wait. While this isn't a gas pedal sticking or failing brakes, it does I believe speak to the over-all safety concerns relating to Toyota as a worldwide manufacturer. Please remember, the scion is totally manufactured and assembled in japan (not by the u. S. Work force).