Strange electrical happenings #2

To the best of my knowledge there's no alarm in my Forester. I didn't buy one, and I've seen no evidence of one in the three years I've owned it--until just recently. Twice lately the horn has decided to start beeping when I did something involving the remote or the locks. Each time I got it to shut off with a combination of multiple on/off with the key or presses on the big remote button.

I can't reconstruct my exact moves that led to one of these situations, but I'm quite certain what I did the other time. However, doing it again didn't product the same result.

Panic alarm perhaps? Bouncing contacts on a switch or a relay that turn one press into multiple ones?

I didn't RTFM on this one.