I recently replaced the master cylinder in my 2002 buick, and after bleeding the line, the brake pedal was still going all the way to the floor. Is there another problem that this could be pertaining to?

Sounds like air is still trapped somewheres. Air in lines will eventually migrate to the cylinder or caliper furthest away from master brake cylinder (at least in the old days). Also with rams, brakes are adjusted through pumping pedal, may end up with low pedal or other issue (i.e.- fluid too low now in reservoir). A slight drag on wheel would indicate adjustment is good usually.

Other car has clutch hydraulics (6 speed manual) using same reservoir as brakes do. Seems to work but also look for unexpected things as that. Definitely not Buick mechanic by a long shot.