"Today's the first I've heard of it," Redmond said Friday. "He tried to take a few swings, and it just was tight."
The Marlins are uncertain when Morrison will be able to return to the lineup.
"Usually, back things are more than just a day," Redmond said. "I would assume he'd be out for a couple of days. We'll see. Hopefully not."
Redmond benched Morrison for Wednesday's series finale against the Brewers in order to give the 25-year-old an extra day of rest in addition to Thursday's off-day.
Following Tuesday night's 5-4 win against Milwaukee, Morrison had played five straight days -- two contests with Double-A Jacksonville and three with Miami.
Rookie center fielder Marcell Ozuna moved up from fifth to fourth in the order to account for Morrison's absence. Greg Dobbs replaced Morrison at first and was inserted into No. 7 hole, bumping shortstop Adeiny Hechavarria up to sixth.
Morrison, who underwent right knee surgery in September, is batting .444 (4-for-9) with six total bases, two runs scored and a .545 on-base percentage since he was reinstated from the 60-day disabled list on Sunday.
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter