Tony,
i believe this to have happend.....the wheel bearing took care of your original problem. NO the wheel bearing "kit" does not include a pinion seal nor does it have anything to do with it. what i believe happend next is that after replacing the pinion seal the technician OVER torqued and ruined the bearing.
you have a z28, this is a camaro im assuming?
i spoke with one of the master techs here at work and he was very familiar with this issue occuring on g.m models..if the technician that replaced the seal was not careful he couldve easily overtorqued and now you need to replace the bearing. this should be taken care of at no charge to you