Yup, likely ball end. It can happen if you string up and forget to pull up on the string when you press the pin down onto the bridge so it holds for a while, then, SNAP, it settles in. Either this or a defective string. That happens too, and is rare, but does happen! FWIW, I had a defective G with a set of elixirs once and they sent me three of that string within days.
Edward