Yes! It does happen!
You played your guitar the night before and when you pick it up in the morning, the action on the instrument is sky-high.
This happens more often than not due to humidity – too much humidity – which is not often discussed. It is also possible that the neck may have moved during the night, causing the strings to rise over the fretboard.
A friend had this very expensive guitar which he used to religiously humidify. In fact, when he used to return the instrument to its case, there was a humidifier waiting there to feed it!
So, one fine day, when he picked up his instrument to play, he could hardly play it. Astounded, he checked everything and when he could not find the problem, rushed over to show it to me. Here is what I told him:
“When you are hungry, you eat, and you continue eating till you are full. What would happen if you continued to eat even after you were full?”
“I would bloat,” he said, still puzzled at where I was getting with me targeting his gastronomical proclivities.
“Exactly!” I said. “Your guitar has had too much to eat, or rather, too much to drink. The bloating is due to the fact that the wood in your instrument has taken in way too much water than it required. In fact, you can see it here”. And with that I took a 12″ ruler and laid it across the top just under the bridge. While the centre of the top was in contact with the ruler, the ends of the ruler were high in the air, just like this:
My advice to him was to loosen the strings, take the humidifier out of the case and not to humidify the instrument at least for three weeks.
My friend got back to me in two weeks to report that the instrument had lost its belly and the action too was back to normal. I asked him maintain the no-humidity regimen for a week more before he started humidifying his instrument again.
My next piece of advice to him is also the advice I give you.
“Of course, you must humidify your guitar but then you must know when your guitar has had enough to ‘drink’. You will only know this if you have a small but reliable hygrometer kept INSIDE the guitar itself. Having a humidifier in the case of the guitar will never give you a very accurate picture of the humidity level of your instrument.
This instrument might appear large but fits easily in your palm and also inside your guitar.
After every four or five days check the reading on it, and once your guitar reaches that optimum range (45% – 55%) of humidity, stop feeding it water.
Relatedly, the tension of the strings acting on the neck might cause it to bend one way or another. A simple, 1/4 turn of the truss rod should be enough to correct the problem.