When having a crown glued back in the dentist used a bleach solution to clean tooth. Normal?

Yes. Proper cleaning of the residual tooth surface prior to capping with a permanent crown is a good call.

Yes, Sometimes disinfecting solutions or cleaning agents are applied to teeth prior to cementation of crowns to prevent sensitivity or to remove any residual debris

Hi:Hydrogen Peroxide is routing used as a disinfectant before crown cementation.  This is absolutely normal.Best,Dr. Maddahi

Sometimes disinfecting solutions are applied to teeth prior to cementation of crowns to prevent sensitivity.