I doubt very much the brass was once fired. Unless there was a very significant headspace problem in the rifle, you will NEVER get incipient headspace separation on once fired brass. In addition, as noted above, it's highly unlikely one would size and trim once fired brass they were intending to sell.
You should be pissed.
I have bought LOTS of once fired brass but only from trusted sources. Thus far it has worked well for me. There has been a trend, since the Obama reloading scare, for every Tom, Dick and Harry to sell small lots of range brass and, surprisingly, people buy them. I generally only buy large lots (say 500 to 1,000 pieces) unless it's more unusual brass in which case I might spring for as few as 100.
