In reply to crayefish:
If you use the word "rust" in the every day English use as "corrosion" (rather than the technical use for oxidative corrosion of iron, steel) then there are several possibilities.
I've made the mistake of putting some things in the storage box at end of garden when tidying up, supposedly for a week while juggling stuff about and found it again a few years later, to discover some alloys have "rusted" badly. Lost my Markill Stormy that way. Some bits were totally unaffected but the bit that holds the burner into the bottom was rotted where it touched the aluminium body. Maybe some galvanic difference, no idea, but it was ruined
Post edited at 06:51