I have a 2010 Tundra 8 ft bed with less than 20K miles and have had a bed liner purchased through Toyota in it the as long as I have owned it. I found significant rust area in the rear under the bed liner on the drivers side and the start of another rust spot on the same spot on the passenger side. I took it to the dealer and also complained to Toyota and it appears that there will be no support to fix the issue as I have told Toyota that this is a quality issue as it should not have done that with that low of mileage and the protection of the bed liner...does not look like they will stand behind their product. I own a 2005 Sienna also and will replace it this year...and guess what I wont be replacing it with, correct I won't be buying a Sienna.

Update from Jul 14, 2017: Toyota said they would not do anything so I started dug into the rust...it looks like the rust started from the bottom up from a manufactured hole...I have pics from the top and bottom

I bought this tundra brand new off the lot. Had it for 2.5 yrs. I lived in Wisconsin, first winter i notice little rust spot all over the body of my white truck. Took it to the dealer and they told me its just brake dust and so they wet sanded it free once for me. And it just keep coming back during the winter with the salted road. It just bothers me. Makes the truck look like crap. Don't wanna take it back to the dealer cause this time i know they will charge me. But come on a brand new truck less than 20k miles? Does anyone know why this is happening? is it because of the color? The dealer also told me it happens to all cars but because mine is white it just shows more but when i go around and look at other white car/truck i don't see anything like mine. Please help me and what should I do.