Yeah, I heard Vin Scully announce that Penny was taken out because of back stiffness. He must've gotten it after a sac bunt in the 3rd inning. He was topping out at 97-98 MPH and he threw 87 pitches through 5 IP and because SF can be chilly at night, and so that might have added to the stiffness. I don't think it's anything serious to be alarmed about, but I'm hoping he's fine. I would be more concerned if it were more of an arm ailment.
It would be cool to see Chad Billingsley get the callup too.