Press the horn?!! Are you kidding? There's entirely enough honking as it is. Or was: see my following post.Never heard of this happening either. And yes interesting thread read. I had to laugh at picturing this and at first wondered if someone in your house with a remote key or remote access to the car via phone app was honking your horn.
Feel for you that it didn't correct itself after the update (if that's what caused it). What happens when you actually depress the horn?