The team says Anderson is day-to-day.
Anderson walked Derek Norris with two outs in the sixth inning on Sunday, then allowed a single to center field by Wil Myers. But after the single, trainer Stan Conte and manager Don Mattingly came to the mound to check on Anderson, who was pointing to and grabbing his left leg.
Anderson was removed from the game in favor of J.P. Howell, who finished off the inning.
"I felt it a little bit in the Norris at-bat, then on the one pitch Myers it cramped up. You wake up in the middle of the night or when you're stretching you get a calf cramp, usually it goes away. But this was the longest one I ever had. It balled up and wouldn't go away," Anderson said, per the SportsNet LA television broadcast. "I was trying to get through six so we could start fresh in the seventh, but the crap wouldn't go away.
"I'm going to be fine going forward. I just need to drink more water, Gatorade, electrolytes."
Earlier this season Anderson left a start in Atlanta in the third inning with a left Achilles problem, which caused his next start to get pushed back two days.
Anderson walked a season-high four on Sunday, but allowed just one run on four hits in his 5⅔ innings for the win. He has been quite durable this season, with 158 innings in his 27 starts, 35 more innings than he pitched from 2012-2014 combined.
By reaching the 155-inning plateau on Sunday, Anderson earned a $300,000 bonus.