F150 spontaneous alarm activation

It should be warranty still, the alarm goes off when the truck sees that a door is "ajar" without being unlocked and thinks that someone is breaking into it. One of the latches isn't functioning properly.

Check rubber door seal, it might've came out of the rail or any other obstructions causing your door not to close alltheway and eventually pops out, acting like someone opened it.

My 2012 F150 did the same thing. I finally fixed by opening the wiring rubber conduit , between the frame and the doors. In 2 doors I had multiple wires that were partially broken. I put coupling on the breaks and rewrapped the wires. It has been 3 months and has not gone off again.