Assuming this isn't some kind of a joke...
That hiding place is not as protected as you might expect it to be. That film can you found wasn't even damp because it hasn't been there very long. You'll notice that the cache page says the cache is in a magnetic key holder. It's been replaced.
Indiana might be different (though I doubt it), but here in the Carolinas we have a lot of film cans under lamp skirts, and most of them are damp.
Well a friend of mine irl found it in March so it's been there at least that long. We've had some pretty crazy storms since then too. So it seems to be doing an ok job.... But I'm not sure why this would be some kind of a joke