Tiedemann was removed from his start Wednesday at Triple-A Buffalo due to left forearm tightness, Shi Davidi of Sportsnet.ca reports.
In his first start back from the 7-day injured list, Tiedemann was only able to get through one inning (27 pitches) before his forearm began bothering him. Ulnar nerve inflammation in his left elbow has limited the 21-year-old southpaw to just 17.1 innings across all minor-league levels this season, and he'll now presumably head in for imaging to determine whether he needs to miss even more time.