Some cars have auto-lock when you drive off. I wouldn't worry about it. I hate nanny devices like this. Humans have a brain to decide if they want doors locked or not. Ditto auto-headlights and auto-wipers.
Stupidest ideas out. I have yet to use one that is 100% right all the time. Lights come on too early or not at all when it would be nice to have them, so you have to manually operate them anyway (the Ford XR6 setup is horrible). Wipers scrub dry screens, and so on.
I never lock doors when driving. I'm not in Jo'burg! So far I've never had anyone want to get in while the car is moving and I've seen too many door locks jam shut in accidents so you can't get out.
Many cars, including Mazda, (and even my 15 y.o Landcruiser) have an "auto-relock" function that re-locks the car if you haven't opened the drivers door in about 40 seconds after activating the remote-unlocking key fob. This is to take care of the fact that the signal emitted by a key fob can inadvertently unlock nearby cars as well as the car it is intended to open. Those cars so equipped simply then re-lock themselves. That is a good idea as it deals with an issue a human can't deal with, unlike those stupid concepts referred to above..
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