rust on stainless steel rail and ladder

I placed my stairs and ladder in my shed along with my 3 inch tabs. It appears the tablets were a bit wet. The stairs and ladders had quite a bit of rust on them. They were perfect when I stored them. I can polish them with Noxon and they will look ok but I can still see some pitting. They look ok to me but am concerned with rust getting into the water and causing water problems down the road. Is it time for new stairs and ladder or will I be ok. On a side note what may have caused this?? Pool is vinyl, no heater 18 X 36 inground.