Bolton left Sunday's contest against the Mariners in bottom of the second inning with back tightness, Chandler Rome of The Athletic reports.
Bolton was far from sharp to open Sunday's matchup, hitting a batter while walking another and giving up a single and run in the bottom of the first. He then walked all three batters he faced in the second frame before being removed with back discomfort. The right-hander worked his way back from having been hit in his back by a line drive in the first inning of his previous start Monday versus the Rockies, and it's unclear if Sunday's issue is connected to that. More information on his status will likely be provided following the conclusion of the team's series finale with Seattle.