Avoiding SSSS
 

I'm was confirmed on Delta to Athens and a few days before I was to depart I changed the booking to a week later then had the ticket issued. The agent used the original booking and just updated the dates. At the airport I got flagged with SSSS.

I think the agent should have created a new booking as I think the history of flights in the original one flagged me.

Does that make sense? Should I blame Delta for this?

You called exactly what happened. However, no airline will make a new booking for a date change. You should have cancelled the first ticket and made a new booking yourself.

You should blame Delta, not for keeping the old booking, but for agreeing to use the haraSSSSment parameters that caused them to turn a customer into a haraSSSSee.

HaraSSSSment should be 100% eliminated and those responsible for its use should be severely punished.