4-month-old NEW G17 showing moisture damage on slide

After all I have read about Glocks' Tenifer finish being so rust-resistant, I have to say that I am a bit shocked by this. It's a brand-new Gen 3.

I live 5 miles from the beach, with an average yearly relative humidity of 67% in my city.

I keep my Glock in this 1.5-cubic foot Stack-On cabinet, in which I also keep this...

4-month-old NEW G17 showing moisture damage on slide