In the eighth inning, Kearns was on second base when Jesus Flores hit a ball to right field that looked like it might drop for a hit.
"I went about halfway, then took a look and saw [Phillies right fielder Chris Roberson] catch it, so I went to go back [to second]," Kearns said. "When I planted, my left foot kind of gave out, so I was trying to get back and push off, and that's when it happened."
Manager Manny Acta removed Kearns from the game for Ryan Langerhans.
"He was just cramping up," Acta said. "It was very humid out there and they're sweating a lot. But I'm not anticipating anything serious."
If Kearns is unable to start Friday's game against the Mets, Langerhans would likely get the nod.
Kearns was 2-for-2 with a single, double and two walks when he left the game. He has not missed any time due to injury this season.
Michael Phillips is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.