As you'll note, Hess exited the game after getting one out in the seventh with a no-hitter intact. Hess was at 82 pitches (50 strikes), and while that's not a particularly high count it was Hess' first start of the 2019 season. No doubt, first-year Baltimore manager Brandon Hyde didn't want to take any chances. Some relevant moving pictures:
When Hyde made the trip to the mound after Brandon Drury lined out to short, the Rogers Centre crowd of 10,640 (😁) rained down some boos, but Hess took it with a smile and seemed to be fine with the decision. Shortly thereafter, Baltimore reliever Pedro Araujo allowed a walk followed by a home run to Randal Grichuk. With that, no-hitter and shutout were gone.
After the game, Hyde explained why Hess was pulled from the game:
Had Hess and the bullpen finished the job, then it would've been the first Oriole no-no since Bob Milacki and three relievers combined for one against the Athletics on July 13, 1991.