New York said deGrom's soreness was mild, and the right-hander's live batting practice was delayed to Thursday "out of an abundance of caution."
The two-time Cy Young Award winner has been sidelined since spring training with a stress reaction in his right scapula.
He made his third minor league rehab start last Thursday, pitching four innings of one-run ball for Triple-A Syracuse. He has been expected to return shortly after the All-Star break.
The Mets say he played catch Monday and Tuesday before opting not to face hitters at the team's spring complex in Florida.