If the alloys were refurbished before they sold it (assume 'they' is a dealership) they may consider that the refurb was not part of the warranty.
However if you have other issues, I would make a polite fuss and see what the reaction is. I've never understood why there are so many problems with Lexus alloys and even more puzzled why, after a chance to put them right, they still deteriorate.
2007 is not particularly old for a Lexus and you should reasonably expect a good product for your money.
What mileage is it?
Whether you get a case study or not, I would make a firm but polite 'request' that these things be corrected.
My approach has been to always start from a point of politeness and amiability, don't start stamping your feet until they actually refuse.