My brand new RX330 developed this problem at 200 miles! The dealer originally resurfaced the rotors, but, at my insistence, replaced all 4 rotors and brake pads.
I also have a front end shimmy at high speeds, and a continuous pulling left or right, at all speeds. Wheel balancing and reallignment has not solved the problems. Other issues include a roof rack that can not be adjusted, a binding shifter, sterrable headlights that only turn left and a seatbelt installed backwards.