If it's just that spot, it's not a big deal, my main concern is if it grows with time, that's the reason I want to know what could possibly cause this.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
If it's just that spot, it's not a big deal, my main concern is if it grows with time, that's the reason I want to know what could possibly cause this.
You've gone the route of water, maybe humidity?