That may or may not be true. I know many small reputable breeders who vend at our small local expos, and I would have no problem getting a critter from them since they only sell what they produce.
OTOH there are other sellers who will pick up critters from less-reputable mass distributors on Friday to put on their table at a Saturday expo.
I am confused though on the quick turn-around time for the results though - were blood samples set out to a lab for testing? Usually it can take 2-3 days for results on those.