According to http://www.spacex.com/news/2013/02/09/falcon-9-flight-1-pictures , ...

trothamel on Sept 29, 2013 | parent | context | favorite | on: SpaceX Launch - Official Webcast

According to http://www.spacex.com/news/2013/02/09/falcon-9-flight-1-pict... , it's the nozzle stiffening ring.

I'm guessing that it's there to help with handling the incredibly thin nozzle extension in gravity, and that once the craft is in freefall (or under exhaust pressure) it's no longer necessary.

emp_zealoth on Sept 29, 2013 [–]

Thank you so much, I'm nearly sure this is what I was asking about