This is a dealer trying to take advantage of you and then they will bill Lexus also for the TSIB I have listed below. Bring this info in, and they will fix it free of charge in your bumper to bumper period. i just had this done to my car and it is not rattling at all anymore.

Rattles: Performed TSIB #NV003-06. NV50148 06IS250 and IS350
Parts: 08231-00801 Noise Kit
08231-00810 Wind Noise Kit
Labor: Applied TSIB NV003-06 NV5014 A 2.20. Removed instrument panel and insulated panel clips, HVAC ducts, and defroster nozzle.

 

The 12 mo/ 12,000 sounds like something he made up on the fly. BUT I bet he can find something in the warrany documents that excludes things like rattles. Remember that the dash rattle is covered because is is a TSIB.

 

That will never fly with Lexus. Perhaps some other manufacturer but not Lexus. If a dealer gets caught doing thsi the will be in a heap of ****.