Waiting to hear back whether my wife's MacBook Air qualifies for free upgrade, I think it will since it was bought from the Apple Refurbished Centre a week after WDC but we'll see. I'll upgrade regardless, just don't want to spent the $20 if I don't have to.
You should be good for the free upgrade. It applies to most Macs purchased after June 11, whether from the apple store or refurb store.