Triple Honk when powering down car...

Earlier today I ran through the drive-thru at Dunkin and then parked for a moment to get situated before taking off again. My fresh coffee was cold, so I shut down the car to go inside and get it replaced.

The instant I turned off the car, it startled me a bit with the dreaded "triple honk"...

There were no messages on the DIC or anything. I was able to lock and then unlock the doors with the button on the handle, and it started back up fine, without any messages about the remote or anything. Random anomaly, or was it trying to subtly tell me something?

Edit: I should note that all the doors were closed when I shut it off, as usual.