He's got an auto which cuts fuel a bit later than a stick (the DFSO tuning is less aggressive stock).
Brett, I'd try to verify with a second wideband just to be sure - sensors tend to get lazy and drift as they age before they go out. I keep a couple on hand for that very reason.
Also, did you get that graph from #s out of Innovate software or out of your twEECer datalog?
Wes