Not sure that rust is the right word, but I have 2 brand new stainless racking arms with the same issue. There is a white powder and straw/brown discoloration inside both tubes right where the "indicator" rod was tacked onto the outside of the tube. I've scrubbed down to bare metal with barkeeper's friend, and run through a citric acid passivation step (4% ~1hr at 140F), but it keeps coming back. Sorry, really hard to get a good picture. Any ideas what it could be, and what to do about it?