Cliff Lee suffered a muscle strain near his armpit, but says he is healthy now:

I was just playing catch in the offseason. I had a little minor, something going on in my arm pit. I Called the trainers, went to Philadelphia, and they diagnosed it. I didn’t throw for a few days, built back up and here I am. I’m perfectly fine and right with everyone else. It’s not really a major issue.

When someone signs a big, long-term contract, nothing is minor.