Shanahan described the surgery as a "chest" procedure during his news conference Thursday. But in an interview with ESPN's "NFL Live" on Thursday, Garcon said the surgery was actually on his labrum, a type of cartilage in the shoulder joint. He didn't specify which shoulder was injured.
"It was a small surgery; it wasn't nothing major," Garcon told ESPN.
Garcon caught passes Thursday from quarterback Robert Griffin III, who is recovering from surgery to repair ligaments in his right knee. The two players worked with a group of players practicing apart from the rest of the team.
Shanahan said he expects Garcon to be cleared for training camp.
"I think Pierre, his rehab has been unbelievable," Shanahan said. "Anytime you get operated on like he did and you're able to come back as quickly as he has, I was watching him this morning in the weight room, and he was lifting weights that he shouldn't be able to lift.
"And he feels very comfortable, and it's been a slow process. But he's in excellent shape, so I'll be surprised if he's not full speed, ready to go once we go to training camp."
Shanahan said something "came out" during the Redskins' playoff loss to the Seattle Seahawks, prompting Garcon to have the surgery.
Garcon signed a five-year, $42.5 million contract with the Redskins before the 2012 season. He tore a ligament in his toe in the Redskins' season opener and missed six games. He finished with 44 receptions for 633 yards and four touchdowns.