general problems of the 2004 Infiniti FX35

Had car checked by mechanic who said when checking under the car, he found it rusted to the point which it could become unsafe. I checked online for recalls. Found recalls for Nissan pathfinders and Infiniti i30. Not the fx. However there were many forums of other Fx35 owners who also claimed their cars had rusted under the car. My car has very low mileage for the year. It is in new england, but my driveway is hot topped and always cleaned to the bare pavement. I do not use rock salt. I also live and work in my home, so I am not on the road a lot. I am passed the time on the warranty, but my mileage is low. Spoke to someone at Infiniti, but she didnt believe I would be eligible to have it fixed unless there was a recall. Nissan had this problem with other cars, and stands to reason that it could also apply to this model. Could you please investigate? this is a very expensive car. Thank you.