Stainless doesn't mean rust free. stainless is particularly sensitive to chloride pin hole corrosion.
That's why you sometimes get rust spots on cutlery in dishwashers (btw don't wash dirty car parts in it unless 'er indoors is out
)
I got stung by that once - had a bike rear hub baking nicely in the oven, a couple of bearings in the freezer, and half my tool kit in the dishy, when she came home early.
We had a rather expensive meal out that evening.....
