so does this affect the 2009 is-f? your list says 2008 is-f.I've seen the TSB (TSB2618) for the new accessory drive belt tensioner assembly.
Some customers may experience an abnormal noise from the engine accessory drive belt area. An improved accessory drive belt tensioner assembly has been developed to keep the tensioner pulley in alignment with the other pulleys. If the tensioner pulley is out of alignment, use the procedure in this bulletin to address the customer’s concern.
It's for all these vehicles:
2008 GS 460
2008 IS F
2007-2008 LS 460
2008 LX 570
Unless it's making noise there isn't anything to worry about. FYI - this is the Canadian TSB.