Just a point, when a disc rotors warps; the metal gets too hot & expands, either they get a buckle in them or the outside gets bigger than the inside they can ‘cone’ - the outside moves to the left or right.
Visulise it for a moment.
This will flex somewhat. Check the rotor is flat with a straight edge to be sure
Change the fluid while you are at it. Check the vent hole in the master cyl cap is clean too.
Sometimes the calliper pistons get a bit seized up & don’t want to move or return fully. Take the pads out & Pump them out a little, clean them & push them back.
You can carefully use a cheap wood sash or G clamp for this, but don’t go crazy.
Sometimes the fluid picks up dust that becomes sludge & this falls to the bottom of the system. . . which is just behind the pistons.
Often on an old bike I will remove them by pumping them out evenly & this gives you a good chance to clean the pistons properly & any gunk in the calliper + inspect the seals.