Cobb left Tuesday's start against the Phillies after three perfect innings despite being slated to throw four innings. After the game, the 27-year-old said he was not worried about the tightness.
"If it was something I was really concerned of, I probably wouldn't have thrown today at all," Cobb said. "This was something I knew about."
Last season, Cobb finished with a 10-9 record, a 2.87 ERA and 149 strikeouts in 166.1 innings.
The Rays open the regular season on April 6 against the Baltimore Orioles.
- Paul Palladino