I have the same problem with my m&p 9 - rust on the slide, sights, and "stainless steel" components - mostly on the fish scales. I assumed it was because of the high acidity in my hands. I had the same problem when I was younger and played the trumpet. The brass and silver would deteriorate because of it. With my gun, however, I have been religious about maintaining/cleaning it since I had the rust issue. I noticed it a couple of weeks ago. I would come home from work, take it out of the safe and dry fire it several times for practice and then put it back in the safe. This went on for about 2 weeks. Finally, I took it out to take it to the range and it was covered in rust. I don't know if it was an over-night visible change or if I just didn't notice it before, but it was pretty bad. I had to take the toothbrush to it with some cleaning oil for about 1/2 hour to get it back to shape. Although I am confident that S&W will be good about fixing the situation, I don't want to wait several weeks to get it back. I am very interested in seeing how things work out for you - make sure you post your results when you get the gun back.