I absolutely agree with "hlevin". At the price we pay for these cars, I expected to hear virtually nothing- no brake noise, no engine noise while idling...I've had the car in a couple of times now for the brakes and other small issues and been told that the noise is 'normal'. I've not been informed of a TSB.
I will say that my Lexus experience has been quite disappointing and has had me questioning my decision of my purchase over a Mercedes Unfortunately since all of this drama has come about with Toyota, our car values have dropped significantly- check them out on NADA or Kelley Blue Book. Suppose I'm stuck with it for a while-