Problem solved. I did the FTer staple: politely hang up and call back and get another agent. He booked the flights as requested with nary a mention of an illegal connection time. I hope and expect that 58 minutes will be enough to go from CO to DL in ATL, and if not, there are several later DL-operated flights between ATL and NYC to use as backup in case of an emergency. Glad it all worked out. Thanks, Delta. ^