beeping noise!!!!

[FL318i]

:confused:ok so the other night my wife is driving and she said that she heard a beeping noise coming from the car, and me like a smart:cool: told her that she is coo coo!!! and tonight i made a really fast turn and i heard the beeping....it goes like this: beeep...beeep...beeep (:p).
what is it?? is it normal?? am i going coo coo too???

thanks in advance!!