Bad bearing would make sense- the rotor doesn't look damaged really, just taken a little of the epoxy off the kevlar strands ( if it was damaged too much then the magnets would have shattered during use ). If only one bearing is bad, I would just replace it with something a little better- there are top-quality bearings for ~$1 each if you look around ( Boca bearings, or Acer ceramic bearings are great ).
Otherwise, you could pay ~$25? for a new rotor and 2 new bearings ( repair kit ), or send the motor to castle to have it inspected and the bearing/ rotor replaced if required.
Remember that this is just a section on a forum website, it is not an official support forum that is monitored or staffed by castle reps on a permanent basis- if you need specific help or info about repairs, you need to contact castle more directly.