Pennington, who has undergone two surgeries previously on the shoulder, was hurt when he was hit by blitzing linebacker Kevin Burnett.
"I've been down this road before and I'd hate to speculate because there are so many different things that can go on in there that I'd be wrong to try to guess what it is right now," Pennington said after Sunday's game. "The doctors just told me to keep it tucked right now to not do any further damage and not to mess anything up that's not messed up. I just tried to be safe with it and keep it close to my body."
If the injury indeed is serious, it would continue a strange pattern in Pennington's career where he always sustains a significant injury in odd-numbered years and has great success in even-numbered years.