That wasn't the Rinnegan Obito was using.
Since the zetsu that showed up was a white one, I think it came from stealing the other Rinnegan that was in Nagato's dead body. Obito was only using the left eye, and now Madara has the right one. That wasn't the Rinnegan that Obito currently has in his body, although that one will soon become Madara's again as well.
Since the zetsu that showed up was a white one, I think it came from stealing the other Rinnegan that was in Nagato's dead body. Obito was only using the left eye, and now Madara has the right one. That wasn't the Rinnegan that Obito currently has in his body, although that one will soon become Madara's again as well.