Gibson did not sound optimistic about playing on Saturday night against the Charlotte Bobcats.
"The [training staff] said if anybody asks, just come back and talk to them about [the injury]," he said.
When asked if he was day-to-day, Gibson responded, "I don't know, we'll have to see."
Bulls head coach Tom Thibodeau said both Gibson and backup point guard John Lucas III, who sustained a left groin injury, would be re-evaluated on Saturday.
"Day to day," Thibodeau said. "They're nicked up a little bit, but they'll be fine ... [athletic trainer] Fred [Tedeschi] will have a better read on it [Saturday]."
These latest injury woes come on top of the fact that Bulls point guard Derrick Rose missed his third straight game because of a toe injury. He did not speak to reporters after the game.
Lucas, meanwhile, said after the game he would be fine.
Bulls center Joakim Noah tweaked an ankle injury, but he said he would be ready to play on Saturday night as well.
Nick Friedell covers the Bulls for ESPNChicago.com.