This came from Rotowire yesterday:
Mauer reported soreness and mild swelling in his surgically repaired left knee on Monday. "He was doing his workouts and said he felt something on the top of his knee. Felt a little swelling and a little tightness," manager Ron Gardenhire told the Minneapolis Star Tribune. "If it remains then, obviously, we'll have to get him checked out. We were told this should not be a big deal but that doesn't mean a whole lot. That's like spitting in the wind." Mauer was held out of Monday's spring training game as a result. This is a red flag for Mauer as soreness that was called normal at times last summer resulted in him being put on the shelf for weeks. If Mauer can't play at catcher this spring, the Twins would have to re-arrange their lineup with Mike Redmond and Matt LeCroy getting more at bats and Mauer getting more time at DH, or possibly making a position change to third base. Watch his status closely this spring to see if this is a minor setback or signs of something more serious.
Then they have this today:
Mauer (knee) was able to take batting practice on Tuesday after he missed Monday's game with soreness in his surgically-repaired knee, ESPN reports. "They're all worried, but I knew coming into spring that something like this might happen," he said. "The doctors told me that it might feel weird for a while. I was prepared for it, but it still kind of stinks that it's coming up." While Mauer and team doctors say this soreness is normal in his recovery, this setback raises doubt after similar soreness last season turned out to be something worse and put him on the shelf for most of the second half. Watch his status closely this spring.