JUPITER, Fla. — A relatively low-key Mets spring training added a twist of drama Monday, when the club disclosed Matt Harvey could miss his Opening Day start because of an ailment that has arisen.

Mets officials would not disclose the ailment — other than to say it was non-orthopedic — but Harvey was scratched from his final scheduled exhibition start Tuesday as the club awaited test results.

“It is not orthopedic — his arm is fine,” manager Terry Collins said. “His arm is fine.”

Harvey celebrated his 27th birthday Sunday and team officials were originally wary the righty had partied too much when he called in sick Monday morning. But after Harvey described his symptoms to the team’s medical staff, he was sent for examination by a doctor.

“It’s a non-baseball issue that he’s got to address and it came up this morning and as a result, he won’t pitch [Tuesday],” general manager Sandy Alderson said. “We’ll just see what happens with follow-up tests and consultation.”

Alderson indicated Harvey was still in Florida, but could be sent to New York for further evaluation if needed.

A person with knowledge of Harvey’s medical issue termed it “not major” and indicated the pitcher’s worst-case scenario would be getting pushed back in the rotation or skipping a turn.

“If he had to have a wisdom tooth pulled, he wouldn’t pitch [Tuesday], so let’s not jump to conclusions,” Alderson said.

Harvey’s absence was conspicuous on a day the entire team traveled to Roger Dean Stadium — as a bonding exercise — for an exhibition game against the Cardinals.

Harvey’s most recent exhibition appearance came Thursday, when he allowed six earned runs over three innings against the Astros. Sean Gilmartin will pitch in his place Tuesday against the Marlins, and Collins can go a variety of directions for Sunday’s opener in Kansas City if needed.

“We’re very lucky to have the pitching we’ve got and if [Harvey] can’t go, we’ll have somebody else ready,” Collins said.

But Collins, when asked if Monday’s starter, Bartolo Colon, would be a candidate to pitch in Harvey’s place, also warned it was too early to make contingency plans. Jacob deGrom is a logical candidate, but his wife, Stacey, is expecting the couple’s first child next Tuesday, which could preclude the righty from pitching in Kansas City. As it stands, all indications are deGrom will pitch the home opener a week from Friday.

“I think it’s a little early to attach any level of concern [on Harvey],” Alderson said. “It’s way too premature for us to be discussing anything related to Opening Day. I understand Opening Day is not too far away, but we’re dealing with [Tuesday] and we should know something more [Tuesday] or the next day.”

In three appearances this spring, Harvey is 1-1 with a 6.30 ERA. Harvey, like the rest of the Mets rotation, rested for an extra week at the beginning of the Grapefruit League schedule to get extra rest after a 2015 season that extended into November because of the team’s World Series appearance.

Harvey is not expected to face an innings limitation this season. Last year, in his return from Tommy John surgery, the righty skipped starts in the final two months of the regular season. Harvey pitched 216 innings overall, including the postseason.