This just happened last night on my 2018. No evidence of foul play. Any ideas?

 

Not sure if you have an aftermarket alarm or not.

However it could've been from vibration from a truck or even car audio speakers bass.

 

Bought it used on a lease turn-in.. I would reasonably assume this was factory install. The lights/horn flashed. The horn stopped but the lights continued to flash until I shut it down with the key-fob

 

Is this the first time it has happened? Or has it been happening on a regular basis?

 

This is the 1st time it hapened. The factory warranty concludes on Jan 1 and not sure if it would be an electrical issue. I have never experienced this.

 

Other than the obvious of someone grabbing the door handle or a cat jumping on the windshield, etc it could be the battery in your remote is dying or the alarm actuator is going bad.

Did it turn off once you clicked the remote? If it did, it probably is not the actuator-possibly the battery but likely something triggered it. Heck, wind can trigger an alarm.

My Wife 2018 BMW alarm actuator went out and the entire thing stopped working. It was around 2am when the alarm went off and I couldn't use the remote to unlock it and couldn't get into the car to open the hood and disconnect the battery. My neighbors loved me.

 

Could it be you somehow, accidentally without realizing it pressed the alarm button on your key fob? I only ask because what you describe is exactly what happened to me a couple times now. In one case I had some odd shaped thing in my pocket where it collided just right with the key fob when I sat down in a chair. Yesterday I had my hands in my pockets and accidentally pressed the button. I'm listening to a car in the parking lot with an alarm going off and wondering what idiot has his alarm going off; it's me! IDK, it was windy yesterday. Maybe it was the wind?!