Kazmir, 31, said he thought his problem might've been caused by dehydration on a muggy evening.
"That's kind of what it felt like -- just a little bit of tightness, maybe like cramping or something like that," Kazmir said. "It definitely felt very minor, and I wanted to go back out there and still pitch."
Kazmir allowed an unearned run in the second inning Wednesday night but otherwise pitched well. He gave up two hits and struck out four, including Alex Rodriguez twice.
Kazmir left his start May 27 with shoulder tightness. An MRI showed no damage. He was on a recent roll before Wednesday's start, going 3-1 with a 1.53 ERA over his prior five starts.
Information from The Associated Press was used in this report.