Your location says upstate NY... I'm wondering how far upstate? I live in the Finger Lakes, between Rochester and Syracuse.
I've never been a lover of heat and humidity, so am very thankful for AC - but we did not have it until 10 years or so ago. We do have 2 dehumidifiers in the basement as well.
Even before the AC, though, I don't remember anything inside getting rusty. Is it possible that there was something in the caddy that wasn't stainless? Maybe that's how rust got on them?