i've noticed a strange phenomenon since starting to drive my 280 regularly over the last few weeks. it only seems to happen when i'm in my parking garage, although it did happen once in my driveway. when i'm pulling away from a stop and going under 5 mph, and start pushing on the accelerator, occasionally it makes the horn beep. i have no idea where to even start with this. it did not do this before i took it to my body shop. they removed the horns to paint the front end, and they said they did a little wiring work on the headlights, but i don't think they've touched any other part of the electrical system. thoughts? on an unrelated note, my gas gauge drops and rises in association with how much voltage i'm getting. normal or problem?