I would put money on the condensation thing. I had the exact same thing happen to me last weekend during a 3 hr drive with the top down in 85 degree heat and the AC blowing on my feet. Scared the heck out of me first time it dripped on my foot as I was wearing flip flops. Continued to do it until I turned the AC off.
if you have the alarm option, make very sure none of that moisture reaches the CPU box under the seat. There are numerous threads about the system going haywire after any sort of bath, good luck.