Stewart was outrighted to Triple-A Gwinnett on Friday, David O'Brien of The Atlanta Journal-Constitution reports.
Stewart received unexpected playing time in the opening week of the season with Tyler Flowers (oblique) and Kurt Suzuki (hand) both out injured. With Suzuki now able to return and Carlos Perez in the fold, Stewart was no longer needed, so he'll return to being organizational depth at the Triple-A level.