The Cubs made it almost two-and-a-half hours into their first full-squad workout before Matt Garza reached his first “what the hell?” moment. There’s no need to panic, as Garza appeared to be confident and upbeat when he stood in front of his locker late Sunday afternoon trying to make sense of what the Cubs are calling a mild lat strain. But the optics at Fitch Park didn’t look good at 2:25 p.m., Garza stretching his left side to get loose, consulting with manager Dale Sveum and pitching coach Chris Bosio before walking off the field with head athletic trainer PJ Mainville. “It’s not as bad as I thought,” Garza said. “This shouldn’t be a big thing.” Garza cut short the live batting practice 20 throws into his 40-pitch session. He hadn’t faced a hitter in almost seven months and spent the entire offseason letting the stress reaction in his right elbow heal, trying to get into the best shape possible, mentally and physically. Garza estimated he was throwing 80-to-85 percent and felt something like a cramp. He faced Javier Baez, Steve Clevenger and Christian Villanueva before stepping out during Jorge Soler’s turn. “My arm felt fine, so I was pretty pumped about that,” Garza said. “(But) I’m not going to push it when I don’t have to.” Garza will be re-evaluated on Monday and Sveum said it was too early to tell whether this would impact his rotation plans to start the season. Even if this wasn’t the worst-case scenario, it was still a little frustrating and disappointing for Garza, who has felt like he’s been locked in a cage. “I’ve done everything you could ask,” he said. “It’s just patience. Got to sit back and just let things heal now, I guess.” Over the winter, Garza vowed to be ready by Opening Day, but this time he didn’t want to make any bold guarantees. It goes without saying that this is a huge year for Garza, his final one before free agency. In all probability, he would have been traded at last season’s deadline and working out at another camp in Arizona or Florida if he hadn’t injured his elbow.