Well, in fact it was sitting at the gate without budging an inch for 30-35 minutes after the door closing and jetway removal and I know for a fact (from flytecomm.com on a DFW AC computer I accessed before going to the gate) that the flight plan on file with the FAA had an approved departure time a few minutes after the doors were closed. So yeah, it was most definitely a case of a ground crew not being available for pushback and I find it hard to believe that the Captain would fabricate a story like that.