Stewart went 1-for-3 with a walk and a two-run home run in Monday's win over Atlanta.
The 30-year-old came into the game having gone 0-for-10 to start the season, but Stewart broke a 5-5 tie in the eighth inning by launching a Pierce Johnson curveball over the fence in center field. Stewart has been the Mets' regular DH against right-handed pitching to begin the season, but he'll lose that role -- and potentially even his spot on the 26-man roster -- when J.D. Martinez (body soreness) is ready to make his debut for the club.