I do not know, so my guess is that Ping Pong Productions wanted to edit and air them in the order they wanted. That and there are likely people who are going to be discovering "DT" for the first time with these reruns on a new network, so in the grand scheme of things, not sure if it matters so much. Hope I don't ruffle feathers by saying that.
As far as the book, it documents the history of "DT" in relation to it's original network and came out more than a year before these reruns found a new home on Travel Channel. I hope that clears things up! On that note - the price of the book has been lowered to celebrate the show's revival - it is full of exclusive interviews, insider info, and even a foreword by Josh Gates himself! Pick it and support the fan site by clicking here. -Amanda, fan site runner