"I just came out here today, did my normal stretches and it was tight," Miller said. "(But) I'll be fine. It will take a couple of days to heal and I'll be ready to go.
"I've had it before. Basically today we just wanted to be smart with it. It got tight and started to spasm. Whether it was the heat and being dehydrated or what, I don't know."
The Bears starting quarterback, who signed a five-year deal during the off-season, has had a history of health problems. Miller suffered a torn Achilles' tendon in 2000. A strained a hamstring forced him to miss the first two weeks of training camp last season. A hip pointer caused him to miss a game and a half midway through the Bears 13-3 campaign.
Although, the injury is considered minor Miller will likely sit the remainder of the week but could participate in practices next week. The voluntary practices run through June 21.
The majority of the team participated with the exception of Bryan Robinson, Damon Moore, Keith McKenzie and Marcus Robinson all of which are recovering from injuries.
On a positive note Miller did say he has fully recovered from a separated right shoulder, which he sustained in the Bears' playoff loss to the Philadelphia Eagles.
"I feel healthy, other than today obviously being tight," Miller said. "But I feel strong physically and I'll be ready to go."