Turns out it was good news for Karstens, who dealt with a groin injury in 2008 and did not want to repeat the experience.
"Right now, it's day to day. It feels a lot better today than it did yesterday," Karstens said. "I didn't really want to take it any farther, because I didn't want to aggravate it any more."
Karstens was also relieved that the injury didn't come to his already injured shoulder. He hasn't appeared in a Major League game since April 17, when he pitched an inning against Arizona. Karstens was placed on the 15-day disabled list on April 18.
"It's extremely frustrating, because I've been working so hard to get back," Karstens said. "This was supposed to be my last outing.
"[The shoulder] feels great. I haven't had any -- knock on wood -- any setbacks with my shoulder. So, that was definitely a positive for me."