Chattering After Initial Startup

[is350ace]

Hey guys. I have about 45000 miles on my is350. Whenever the car has been sitting for a while (in the morning, or leaving work), it gives a short chattering sound right after I crank it. If I turn it off, and crank it back up... it doesn't do it again. But after it has been sitting a while it will. I plan on calling the service guys today, before that 50k mile mark especially, but does anyone have a idea at what it could be. It's almost like the oil hasn't gotten to the valves yet.

[bartkat]

It's the camshaft timing gear. The TSB is here.

http://faqlexus.com/attachments/52/EG019-0...d%20Startup.pdf

[is350ace]

Thanks bartkat. Quick and to the point as usual. I'll call today for an appointment.