Coach Gary Kubiak said Johnson will be OK.
"I think we got lucky," Kubiak said.
Johnson wore a bandage on his finger as he watched the Tuesday afternoon walk-through from the sideline.
Johnson was running a slant route in an individual drill and leaped to catch a pass, with rookie cornerback Roc Carmichael defending. Johnson couldn't make the catch and came down shaking his left hand. He took off his glove, his finger was bleeding and he walked to the sideline, where a trainer examined him.
"As soon as I felt it pop, I felt it out of place and I popped it right back in," Johnson said. "I really wasn't in a lot of pain, or anything like that. It was just more concern about the bleeding and stuff."
Johnson left the field on a cart and went to the hospital. He was back at Reliant Stadium by 1 p.m., eating lunch in the cafeteria with his teammates.
"I wasn't scared," Johnson said. "It's just a dislocated finger. I've had worse. I don't think I'll be worried about a finger keeping me from missing anything."
The 6-foot-3, 223-pound Johnson had 86 catches for 1,216 yards last season, ranking sixth in both categories. He played most of 2010 with a sprained right ankle and underwent surgery in January -- a much more serious injury than this one, he said.
"It's just a finger," Johnson said. "I played with a bum ankle. I don't think a finger is going to keep me out. I'm fine. I'm just letting it heal up, and I'll be right back out there."
Kubiak said he'll wait for doctors to clear Johnson to return to work.
"When he's ready to go, he'll go," Kubiak said. "But it's an opportunity for these younger guys to take some reps."
Second-year receiver Dorin Dickerson took Johnson's first-team reps for the remainder of practice. Kubiak also said cornerback Jason Allen and guard Wade Smith missed some snaps on Tuesday, due to illness.
Linebacker Brian Cushing has sat out team drills for the first two days as he continues to recover from offseason knee surgery. Cushing had an ice wrap on his knee after Tuesday's morning workout but participated in the afternoon walk-through.
"He's a few days away," Kubiak said of Cushing. "I'll have to let you know from day to day. He's the one guy we had who wasn't quite ready to go on the field (on Monday). We're just trying to take our time to do that."
The 6-5, 300-pound Warren was cut by New England after playing for the Patriots from 2003-09. He spent last season on injured reserve with a hip injury. The 6-foot, 250-pound Vickers has played five seasons with Cleveland. Houston is looking to replace All-Pro fullback Vonta Leach, who helped Arian Foster lead the NFL in rushing in 2010.
The 6-foot-1 Maynard played his last 10 seasons in Chicago. He was a third-round pick in the 1997 draft by the New York Giants.
Undrafted free agent Brett Hartmann has been the punter the first two days of Houston's training camp.
Maynard has a 41.9-yard average per punt in his career. Last year, Maynard averaged 40.1 yards on 83 punts, and dropped 24 inside the 20-yard line.
Information from The Associated Press contributed to this report.