A Frequently Asked Question.
It’s a banjo and a banjo is made up of many parts and materials that with temperature and humidity changes tend to expand and contract these parts differently. Added to that it has strings of varying gauges that add a lot of tension to one side of the instrument. The banjo when it’s played is subjected to more tension through the picking hand as the strings are plucked and on the fretting hand when the strings are bent. Some advanced players such as Jens Kruger will purposely bend the neck to achieve a certain sound. Sometines the vocalist or the fiddle player may request a tune or song be performed in a different key to the norm. So it’s little wonder that we have to tweak the tuning ever now and then.
I keep my banjo in one room in an almost constant temperature and humidity and for the most part it stays in tune. As soon as I venture out with it to play at a local jam I am constantly having to retune.
Just be thankful you don’t have to tune this little beast.