IIRC, the warranty extension on this problem was to 10 years from the car's in-service date but I suggest you take your car to a Lexus dealership and confirm. It doesn't, or at least didn't, matter if you aren't the original owner.
10 years past the in-service date is a common period for a warranty extension like this. A similar 10-year extension was recently announced on several expensive components on one of our Toyotas after a class action lawsuit settlement.