Today, I noticed a buzzing sound coming from my dash area that sounded like one of those practical joke hand buzzers. I was just sitting in the car with the engine off and radio on, having just driven about five miles to the gas station for a safety inspection. Turned off radio thinking it was static and still there. Took key out of ignition and it persisted for a while then stopped. Then, every now and again, a low grade & very weak buzz for a few minutes until it disappeared. This has happened more than once - I'm trying to learn the pattern to see if it is repeatable before bringing it in for service. Anyone ever experienced this before? Part of the car alarm? Bad solenoid? Ideas?