Got a picture?
Floor joist should not have been notched.
Pipes should not be touching the sheetrock.
Going to need to add nailing plates and shim down the joist.
Another way is to replace the copper with Pex and drill holes in the joist to run it through.

 

My basement was built with the copper water lines notched in the joists and sheet rocked over just like you are talking about and we never had any problems. When I renovated the basement I did replace everything with pex and drilled holes through the joists to get the lines up off the ceiling. The hot water lines don't get hot enough to cause any hazards and it's ok to for the copper to touch any non-metallic objects.

 

It's the condensation on the cold pipes in contact with the paper backing, and the sound of water running through the pipes in direct contact with the rock acting like an amplifier that may cause issues.
Because someone else did it does not make it right.

 

I dont have a picture.

 

A copper water pipe for hot water should never touch/rest on drywall, as it expands when it get hot and then contracts as it cools. It will wear a way the dry wall.

 

Just fur it out with some 1.5 inch wood.