"(It's) not pain," Maddon said Friday. "A lot of guys go through that moment where the arm just doesn't feel right. He came out of the chute really strong and probably went after it too hard, too early. Possibly trying to impress everybody, just being Jon Lester."
Maddon indicated, as of right now, it has no effect on Lester starting Opening Day against the St. Louis Cardinals.
"When a guy smiles easily, talks easily about it, is upbeat, normally it's a good indication," Maddon said. "He was all of that. I feel strongly he's going to be OK."
Lester gave up seven runs in his last outing on Monday against the San Diego Padres. It's unclear if his arm was giving him problems then. Before that game Lester had sailed through his first two spring starts.
"It's not something out of the ordinary," Lester said Saturday morning. "There's no point in trying to grind things out now. If this was April 15, it wouldn't be an issue."
Lester signed a six-year, $155 million deal with the Cubs in the offseason, becoming the immediate face of the pitching staff. He helped the Boston Red Sox win two World Series titles in 2007 and 2013 before being traded to the Oakland Athletics last summer.
Lester will still throw between starts like normal. His next scheduled spring appearance would be next Thursday.
"Our guys feel really good about it," Maddon said. "I checked in this morning. He's feeling great, so we just want to back off a little bit right now."