Noise At Startup On Lexus Es350

I have a 2008 Lexus ES350 and on cold start I get a errrr or knocking noise that lasts several seconds and goes away. I have researched and found recalls for the IS and GS 350s but not the ES. My dealer said this is not the first time they heard of this and wants to charger me $5k to fix. Claims the CAM gears need replaced and the parts and labor are expensive. Lexus corp says no recalls for this on my model and not enough claims received to start a recall. Another site pointed me in the direction of TSB LSB-0028-09 - this spounds like my issue and is from 2010 - should'nt a dealer and Lexus honor this recall. I am very frustrated. To be honest it is quite embarrasing that a Lexus makes this noise and start up. I have had customer/clients and coworkers comment on it. Please advise and provid your advice - thx!