The public release of iOS 9 is a few builds higher than the GM. Users on the GM will be presented an update available pop up.
GM was 13A340. Public release is 13A344.
What you've installed is beta software. That's not exactly the same as the iOS that was released last Wednesday. Did you install public beta, or did you subscribe to Apple's Developer Program?
If it's public beta, the software on your iPhone could be 9.1, if you have updated recently.