undercarriage rust as early as 1 yr from purchase

purchased brand new on May 02, 2012. rust started to form on all welded portions of the undercarriage parts: chassis, suspension parts, brackets, etc. this is particularly annoying because I am the type of owner who diligently wash the undercarriage and even apply silicon spray before wiping dry. it is definitely frustrating to see the rust almost everywhere now thinking that it's only turning 4 years this May and the fact that it had never been used for any off-roading and with less than 49000 kms. Since all the competition is going for a uni-body platform and Toyota is boasting that theirs are the only true SUV with the dependability of frame-on-body platform, you would think that they would make sure the undercarriage is not only tough but will also remain protected by an equally tough paint. the dealer readily dismissed my concern and even tried to contact Toyota Canada but their just pointing me back to the dealer despite the response I got. I guess we're on our own on this one. Hope those considering a Toyota can take heed.