My Honda started itself in the driveway

Last night my '94 Prelude Si (automatic trans) started itself in the driveway. The headlights were on (and the headlight control inside the car was set to OFF), the doors were locked and the Club was on. It was seconds before I was in the driveway and could see no one lurking in the area (or under the car). I unlocked the door, put my key in the ignition, which was in the OFF position, and could not turn the engine off. Finally, I dropped my foot on the brake and that killed it. The headlights went off. I re-started the engine and everything was fine.

The car did come with a remote starter but it has been defunct for at least six years. I took over ownership of the car in late 2001 and have never used it.

I'm sure there is a plausible explanation outside of demonic possession for this?