Hamilton said he was not concerned about the possibility of a serious injury.
"Usually, you know when something is wrong," he said. "I don't have any inkling it is."
Hamilton, 32, was a late scratch from Monday's lineup because of the ankle stiffness.
"It's just weird," he said. "I guess I'm getting older."
He said the ankle first stiffened on him when he awoke Monday morning. With no apparent trigger for the injury, Hamilton explained how it happened this way: "I woke up."