There was no current in it so no short circuits. It was probably dry when you used it if you had used it when wet you would've ruined it.
With no electricity going through it it's just plastic and metal.
So I just learned that USB sticks are actually, like, waterproof. I left one with several months' worth of data on it in my pocket and then put my jeans in the wash. Then when I finally found it I was like OH SHIT ALL OF MY DATA IS GONE!! But then I stuck it into my computer and all of my files were completely unharmed. How the fuck does that even work?? It should be ruined, right??? what the fuck.