Diagnosing a tight Bottom Bracket is a routine maintenance job. Which is a good thing because this is a regular occurrence with ALL types of BB systems.
If the BB is too tight, it will not rotate without grinding or feeling stiff. In fact, if you ever tighten an adjustable (open/loose) BB to an extreme, the BB will not move at all.
If you diagnose this problem in an open/loose system, you must loosen the adjustable cup until the stiffness lessens. However, you will also need to determine whether the BB is bad enough to need replacing, instead of simply adjusting as described. See here to determine how you do this.
Tightness in a sealed BB is a sign that it is deteriorating and it will need to be replaced.
Click here for more information on fixing BB issues.