sounds like the nut needs to be reslotted, which is part of a good setup. I can do truss rod adjustments, saddle adjustments, shim the neck when the saddle adjustment won't do the trick (obviously on bolt neck guitars, not set necks or acoustics). I can radius the saddles as well to match the fingerboard. Filing the nut ... don't have the files and don't do it enough to justify buying them. That's pretty much a one time deal until you've leveled and crowned your frets a time or three. Which I've never had done to a guitar since I've never owned one long enough to need a fret job. If I were going to be doing set ups on new builds or taking in repairs for paying customers then I would spend the money on the files.

There are some neck makers who won't even put a nut on for you because they insist it should be done when the guitar is built and set up for the first time. Or they will install the nut unslotted. That's how important they consider the setup to be.