Hey,
Yup, ive got the same problem. Doesn't happen quite as often as you are describing, but its exactly the same noise (almost like 2 bits of new plastic rubbing together)
Unfortunatey, i haven't got a solution. Will leave that to Lexus warranty with my next service...
only happens to me on certain roads that are quite bumpy. I find pushing clear display part of the instrument cluster panel on the RH side stops the noise. So it appears its coming from the same place on yours.
If you could let me know if yours gets rectificed after you have been to Lexus, that would be great
other than that, they are are great car.
cheers