"We're going to get it checked out," president of baseball operations Michael Hill said. "I don't want to jump to any conclusions."
The team remains hopeful the issue isn't serious, but Morris isn't expected to return for the rest of the road trip, which includes the remainder of the series against the Angels -- which concludes Wednesday night -- as well as a weekend set in Atlanta.
"I'm hoping it is only a couple of days," Hill said.
Morris has worked in the eighth inning, as have A.J. Ramos and Mike Dunn.
Rosters expand on Monday, and the Marlins can bring up more pitching depth then. The team is hoping Carter Capps will return from the disabled list in early September.
The Marlins acquired Morris from the Pirates on June 1 for a Competitive Balance pick in the First-Year Player Draft. With Miami, he's thrown 37 2/3 innings while posting a 0.48 ERA.