One of the most common rip-offs is to do brake jobs before they are needed -- I guess it is a quick way to "pad" dealer profit. Your RX likely has pad wear sensors like the LS so you might as well let the car tell you when it really needs a brake job.
I certainly agree with this statement. I cannot recall all the many times over the years I have been told my brakes need to be replaced immediately and the pads were not yet down to the wear markers. About a year and half ago, when buying tires for our RX300, a tire outfit in this area called Tire Kingdom told me I needed to replace the rear brakes and should not wait even a day longer. I finally replaced the pads about a month ago (about 20K miles later) and the wear markers were still not touching the rotor (although they were very close at this point). Lexus dealers have done the same thing. In my opinion, replacing the pads before the wear markers touch the rotor is a waste of good money. There is still more than sufficient pad left when the wear markers speak up to be completely safe and have new pads installed without panicking.
This problem is not limited to brakes. Last year, with only 70,000 miles on our 2002 RX300, the service adviser at Brahman Lexus in West Palm Beach, Florida told my wife we needed to replace the timing belt for $1185.00. We had a 100,000 CPO warranty on the car and Toyota states to replace the belt at 90,000 miles. Just to note, the independent shop I use would have charged about $400.00 for this job and also replaced the water pump.