Corrosion on Muffler and Tailpipe?

I have a 2016 TRDOR Tacoma about 16 months old. I have noticed a light rust pattern appearing on the exhaust pipe from the joint downstream of the Catalytic converters to and including the muffler and on to the end of tailpipe. I am sure it is stainless. Wondering if that is normal? I believe the factory warranty that applies is 3/36 because the Emissions warranty is specific that it stops at catalytic converters. The exhaust pipes from the manifold and thru the catalytic converters look good. They have a purplish hue to them and am sure they operate much hotter. Anyone have any insight? Tks

 

Normal. Check out the thread on raising the y-pipe and you will see undercarriages like what you are describing. Side note, I have seen stainless rust.