Gonzalez rested on Sunday, and he was pretty optimistic about the injury being a minor one.
"It's only Spring Training, so no big deal," Gonzalez said.
Gonzalez said his arm felt fine throwing on the mound, but his back tightened up, and he wanted to err on the safe side.
"I don't think it's a major thing," said manager Dave Trembley. "It's something he goes through every spring. It's just part of what happens to him."
The 31-year-old Gonzalez hasn't been particularly impressive this spring, allowing an earned run on four hits and two walks over two innings. He's also struck out two and has made it clear that his velocity won't be at its best until the end of Spring Training.
Trembley acknowledged that Gonzalez's velocity is way down, but he said the team has done its homework on its new closer -- including talking to Gonzalez's former teams -- and isn't alarmed.
"That's his normal progression during Spring Training, he will start dialing it up as we get closer to the start of the season," Trembley said. "There's nothing wrong with his arm."
Instead, the lefty with a herky-jerky delivery has used camp to work on using his changeup more frequently, a pitch that could be extremely beneficial given that Gonzalez is predominantly a fastball pitcher.
Gonzalez said on Sunday that he won't be pitching in either of the team's games in Fort Myers, Fla., against the Red Sox and Twins on Monday and Tuesday, respectively, so the soonest he will be on the mound would be Wednesday.
Signed to a two-year deal in the offseason, Gonzalez underwent Tommy John surgery on his left elbow in 2007 and missed most of '08. Last season in Atlanta, he set career highs in appearances (80), innings (74 1/3) and strikeouts (90). Gonzalez has held opposing hitters to a career .209 batting average.
Infielder Michael Aubrey was also taking it easy for the next day or two after he felt discomfort in his right groin during his first at-bat against the Yankees on Saturday afternoon. Trembley removed Aubrey from the game, and Aubrey sought treatment on Sunday to help alleviate some of the discomfort.
Aubrey wasn't sure when he would play next, and after being sidelined for a few days earlier this spring -- for a non-baseball-related procedure -- the first baseman was disappointed with his latest setback.
"It's extremely frustrating," Aubrey said. "[I'm] trying to put myself in a good position, but you can't do that if you're not playing."
In six games this spring, Aubrey is 2-for-9 with one of those hits coming in Saturday's game.
Brittany Ghiroli is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.