You beat me to the punch as I just checked the car and the only indicator near the miles per hour and FE display is the red light for the security system (I think the radio has its own light because the radio will not work if removed and this is a separate security display than the car in general -- something car insurance companies need clarified for a reduction in your premium). That light should only blink when the car is locked though and should not come on if you plug your car in or turn your key but it only comes on after you lock your car so maybe you just never looked at the car after locking it - understood. But let us know about the pop in the speakers or if it happens again.

--> Averaged 685 miles/week and 49.0 mpg in first year (35.7k miles from Aug 7, 2006 to Aug 7, 2007)