Why does my truck unlock?

I purchased the truck out of town and put the second key fob in my computer case. Im back on the road today and have the computer with me. The fob is indeed in the car in the back seat on the floor. I did not realize it was still in the truck. Thanks for all the ideas and answers. I never experienced anything like this with my other key fob cars.

 

That is correct. I've tried often to leave the truck running with my wife and kid in the back, give my wife the key fob before getting out of the truck - she can't lock it (from the fob).

 

If you want to keep the 2nd fob in the cab for some reason, you can disable it / put it in sleep mode. I think you hold the lock button on the fob and then press unlock twice. The lights should blink and then the fob will no longer work. It's in the manual if I've misspoken on the steps.

 

DING DING DING and we have a winner folks..
glad you found it.. happy trucking

 

and this guy also

 

Ahhhh...enlightenment. Happened to me too but my fob had fallen out of my pocket and I tried to lock the truck. Clearly smarter than the operator.