Klein is on the disabled list at Double-A Bowie and will have a precautionary MRI Monday in Baltimore so doctors can get a better look at his shoulder.
Klein took a red-shirt season in 2009 while at UCLA and had an arthroscopic procedure on that shoulder, but he said the current soreness is not related to that at all.
"No, it's not a similar feeling at all to what I was feeling in college," Klein said by phone today from New Hampshire as the Baysox prepared to get on a bus for Maine. "We'll know more after the MRI on Monday but it's just looking like biceps tendinitis and a little inflammation there that flared up. Hope it gets better in the next few days and I pick up a ball next week.
"It was pretty recent (when the soreness began), about a week and a half ago, it was a little tight warming up. It was a little tougher to get loose and it didn't get any better over the next few days so I saw the trainer and got some treatment. They just decided to shut me down, get my arm some rest and knock it out now rather than later.
"I saw (Orioles orthopedist) Dr. Wilckens, he came to the field and said it looks like a little biceps tendinitis and I should be fine. He didn't see any major issues or anything. Should be a minor issue."
So he said he doesn't expect any bad news to come next week after the MRI.
"That's what I think is going to happen, hopefully this is just biceps tendinitis and I'll be back out there in a week or two," Klein said.
Klein is having a very good year, going 3-1 with an ERA of 1.11 between Single-A Frederick and Bowie. Over 32 1/3 innings he has given up 23 hits with six walks and 37 strikeouts. His batting average against is just .197.
Since joining Bowie in early May, he was 3-0 with an ERA of 1.08 over nine games.
"I was throwing the ball well but rather take a week or two off now than let it get worse and have to sit out later. It's my first full season, just be cautious and gives this a rest while it's a minor thing," Klein said.
On the audio below, hear an excerpt of my interview today with Dan Klein as he talks about his shoulder injury.