Fuld pinch hit in the top of the eighth inning Monday night and then took the mound with an 8-1 lead.
The umpires said they thought Fuld was sore.
"We got away with violating a rule," Maddon said Tuesday. "There were no shenanigans, no misinformation. I just think there was a miscommunication."
Maddon said Major League Baseball executive Joe Torre called him. Maddon apologized to the umpires. Brewers manager Ron Roenicke said he had no dispute.