My original booking was on 2 separate flight numbers with neither flights being part of the earlier single flight number from AUS->SFO

It was a pleasant surprise at the time that when I was able to get onto the earlier AUS->DFW flt that it also continued on to SFO so I had a shorter connection and didn't have to changes gates at DFW.

I'm not sure if this changes your analysis but we'll see what posts to my account. Right now all I have is DFW->SFO.