I have the same situation with my 7 string .... I'm not so sure that it's from sitting in my house, probably more from being gigged so much and going in and out of widely varying climates.
Unless the frets are seriously sticking out to the point where it's unplayable and you could cut yourself, I'd leave it alone while the temperature and humidity adjust to the seasonal change. In my case, a mild humidity change will likely push the fretboard right back to where it was ..... this kind of stuff happens with natural, unpainted woods ....
