They all have certain moisture levels that will increase and decrease over time. Recently I received a message from a guitar player with a problem. He wrote: " it's been several months now since buying my new guitar. I have a problem with the neck. Three months after the guitar adjusted to the local climate here, there are a butt-load of buzzing frets. Low E string buzzes in numerous places. B,G,D strings buzz in numerous places and 1st fret E and A strings are horrible". "The neck was virtually perfectly straight when it first arrived… almost all of the points at which the fret wires were cut stick out beyond the fret board a small amount, so that when you run your hand up the neck your fingers bump into each fret wire, on the SIDE of the neck…and the fret wire is sharp so it's a very unpleasant experience. It's present on both sides of the fret board".
Hmmm... this is not an unusual problem. Guitars are mostly made of wood and it is the nature of wood to contain a certain amount of "moisture". When the wood loses moisture it shrinks.
This is just plain physics. The metal parts in and on the neck such as frets-are metal, and hold no moisture and therefore do not shrink. Although we level the frets, adjust and straighten the neck, dress the ends of the frets before departure, sometimes the guitar is not treated very well upon arrival to it's new home. Guitars need to be maintained in a more humid environment than you may think. Get a digital hygrometer to help you determine the proper level so there will be no guesses.
The newly adjusted neck will generally "Hump" in the middle causing the, "string buzz in numerous places" described above. It is incumbent upon the player to maintain his/her instrument at an acceptable level of humidity so as to prevent this kind of problem. Of course, players not knowing about the physics of their new guitars will often times blame the builder or manufacturer when in fact they have caused the entire problem. So be a good friend to your instrument. Respect your guitar, take care of it and it will take care of you.