Manager Dale Sveum said Stewart told the athletic trainers that the latest problem isn't a setback. However, the reality is that the Cubs have two weeks remaining before Opening Day, April 1.
"I don't know if he's got enough time," Sveum said. "It'll be interesting."
Stewart was limited to 55 games last season before of a sore wrist, an injury that needed surgery, though that hasn't been a problem this spring.
Whether Stewart is ready for April 1 will affect how the Cubs put together their bench. Brent Lillibridge and Luis Valbuena can play third, as can Edwin Maysonet and Alberto Gonzalez.
"It just comes down to, what do you want in that spot?" Sveum said. "[Steve] Clevenger's obviously a guy who could be interesting, [and we're watching] all the waiver wires."
Clevenger made the Cubs' Opening Day roster last year as the backup catcher but on Saturday played first and third. He could be an emergency third baseman, plus give Sveum more options with double switches.
Others in the mix for the bench spots are non-roster invitees Darnell McDonald, Brian Bogusevic and Dave Sappelt, all outfielders.
"It all depends, when we sit down and really hardcore look at it, what is our need, how does the pitching set up with the other team, who's their closer, set-up guys, left-handed guys," Sveum said.
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.