The Lions improved to 7-2 after beating the Dolphins 20-16. Matthew Stafford threw the game-winning touchdown to Detroit running back Theo Riddick with 29 seconds remaining.
Caldwell said Bush, who has sat out two games this year due to ankle issues, was injured during the game.
"He just got a little nicked up during the course of the game so he wasn't able to do as much as he'd like," Caldwell said, according to Dave Birkett of The Detroit Free Press.
With Bush's injury troubles this year, the Lions have given Theo Riddick a larger role in the offense. Detroit offensive coordinator said last week that he felt both Bush and Riddick could have roles in the offense despite being similar players:
"I think they both have a role," Lombardi told Justin Rogers of MLive.com. "Obviously, they both have certain skills that cross over that are a little redundant, and so in some ways they eat at each other's reps. But they're both very good players, they're both players that can do things extremely well, and so I think you use them both. You try to get them both on the field maybe at the same time."
Joique Bell led Detroit with 10 carries for 44 yards against Miami. Bush had four carries for 20 yards and and one reception for five yards.
The Lions (7-2) play at the Arizona Cardinals (8-1) on Sunday.
- Andrew Melnick