I know this is kinda old but I finally got around to getting the situation fixed after waiting to get is scanned before I took it into the dealer. I found out for sure its the cat, not the O2 sensor and called over to the Chevy Dealer and they said then knew nothing about the 10 yr/120k bulletin, so I called the Chevrolet Assistance number and they were real helpful there as they looked it but and said that my car was covered and even called over to the dealer. As long as they look at it and find its the cat, which I know it is, I get it replaced for free. I go in Wednesday so I'll let people know the final result even though its like 4-5 months later. Thanks for your guy's help and other threads on LS1tech!

 

In case anyone was wondering or for future reference it was a failure of the passenger side cat that caused the code. The dealer replaced it for free as it was covered under warranty.