Montero was prescribed rest and anti-inflammatories for three days and will resume his throwing program after that. Both general manager Sandy Alderson and manager Terry Collins stressed the inflammation is minor.
"We don't expect this to be serious," Alderson said. "But it's another example of what can happen with any starting pitcher."
Montero was summoned from the Minors to help rest the starting rotation amid a stretch of 25 games in 26 days. Left-handed reliever Jack Leathersich was promoted to replace Montero on the Major League roster after Tuesday's game. Alderson implied the Mets could switch Leathersich for a position player now that David Wright isn't expected to return until at least next weekend. That player likely won't be Dilson Herrera or Matt Reynolds, as Alderson doesn't want to pause their development with sporadic playing time.
With two off-days coming up next week and Dillon Gee pitching well after a slow start, Montero wasn't a part of the rotation's immediate future.
He threw well against the Marlins, striking out six and walking just one while his defense plagued him.
Alderson said Montero and others would be considered for similar spot starts down the road, but added that likely wouldn't happen until June.
"I'm sure we'll consider doing it again," Alderson said. "Hopefully, Rafael is ready at that time, but if he is or isn't, we have a number of candidates."
Two of those candidates, top prospects Noah Syndergaard and Steven Matz, are both pitching well at Las Vegas. Syndergaard struck out nine batters in a two-hitter earlier this week, while Matz has a 2.01 ERA in three starts.
Parnell, Black resume rehab
Both Bobby Parnell and Vic Black are back in Florida and began throwing again this week after suffering setbacks in their rehab appearances. Parnell, who is recovering from Tommy John surgery, threw from 60 feet Thursday. He had been shut down with forearm soreness after three appearances with Class A Advanced St. Lucie. Black threw from 90 feet after being shut down for a week with a herniated disk in his neck. Neither is close to returning to the Majors.
"It could be a while," Alderson said.
Joe Trezza is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.