According to the reports, Harvey's absence was noted Saturday afternoon and personnel were sent to his Manhattan apartment around 10 p.m. ET.
Sources close to Harvey told FanRag Sports, which first reported the Mets' welfare check, that he came down with a bad headache after golfing Saturday morning and reached out to the team that afternoon to say he was ill and couldn't be at the park.
Harvey was given a three-day suspension by the Mets following his absence. He is likely to rejoin the rotation Friday at Milwaukee.
"You make a mistake. You stand up, be accountable, and move on. And you know what, people forget about it," Mets manager Terry Collins said Monday, a day after general manager Sandy Alderson revealed the discipline for the 28-year-old pitcher.
Collins said Harvey will return to the Mets on Tuesday and will have to explain what happened to his teammates. Collins said Harvey will decide "if he wants to do it in a group, which is the easiest, I always think, or if he wants to do it individually."
The suspension is costing Harvey $84,016 of his $5,125,000 salary. Collins said he expects Harvey's agent, Scott Boras, to challenge the discipline. Baseball's labor contract says any punishment must be for "just cause.''
Information from The Associated Press was used in this report.