I don't know when the first X-metal appeared, but I know this isn't the first. I snagged a Juliet a few months ago off SAC. They were gone a couple of minutes after being posted, so they didn't have many of them.
Last 24 hours seems to have been good for O on SAC. Juliet mentioned above (why do all the sweet stuff hit in the crazy hours of the morning?!?). They also had grab bag eyepatch up around 7:30PM PST.