What carrier are the flights on and did you change any routing?

If the carrier is AY or BA, then you may have to get them stickered. That can be done at the airport. If you changed a routing, you will need a reissue.

If all you did was a date/time change, then you don't need a reissue. Just have the agent make a reservation.

If you spoke with AA non-RTW-desk, call the RTW desk and they will straighten it out. Otherwise, I would just verify that the agent didn't do anything out of the ordinary and just made a standard reservation.