This rocket was brand new it was the first that would have been SCHEDULED TO REUSE later after this launch.
--quote-- For SpaceX, the private space company owned by Elon Musk, it was the "first launch of [a] flight-proven first stage," the company says. The mission was using the same rocket booster that sent the Dragon spacecraft to the International Space Station earlier this year. --end quote--
Sorry, but that quote is wrong. The first reused booster is (was?) scheduled to launch SES-10 later this year.