There's no reason stated, but NCSoft are changing
their entire billing department's time zone from Eastern Standard Time (EST, -5 hours GMT) to Coordinated Universal Time (UTC, = GMT) starting tomorrow, a difference of about five hours.
As it's just a time zone swap, nobody will lose or gain any hours they've already paid for, but depending on when
you opened your NCSoft account you may be billed a day later in future. It's very important
that you don't think about why they'd make this change, how you can go five hours into the future and not gain any extra time, or why the acronym doesn't match the full phrase. Trust me.