Seabold left his start for Triple-A Worcester on Sunday in the third inning and was checked out by a team trainer, Joe McDonald of the Worcester Telegram reports.
Seabold presumably suffered some sort of injury, the nature and severity of which are not yet clear. He made his major-league debut in mid-September but was sent down after just a single start, so any potential injury likely won't have a significant impact on the Red Sox over the final week of the season.