My bad, I read over the "2 days later" thing.
Well, actually the shown date is not when someone bought your offer. It states when you put your offer up for sale. You can not see when exactly someone bought it.
So the 2 days to which you refer may be irrelevant. Someone needs to look at the database to figure out if everything was right.
But if there really were like 24 hours in between buying and delivering there really may be something else going on. I know of delivery times of up to 4.5 hours per way in bestiaries. But even that added up to all ways usually doesn't result in a 24 hour delay.