Game Center Warning: Attempt to present

Running Unity 4.6.8p8
Reproduced in iOS 8.3 & 9.0

Warning: Attempt to present <GKHostedAuthenticateViewController: 0x16ee8e50> on <UnityDefaultViewController: 0x180849f0> which is already presenting <GKHostedAuthenticateViewController: 0x1817e5f0>

Steps to Reproduce:
1) Make call to Social.localUser.Authenticate()
2) Once the Game Center login screen is displaying, hit the home button.
3) Bring the app to the foreground by tapping the icon on the home screen.
4) The warning will...

Game Center Warning: Attempt to present <GKHostedAuthenticateViewController>