Spoked wheels are designed to be dynamic so that they don't break when stressed.
As the wheel flexes, spokes are detensioned and tensioned, which can cause spokes to loosen (detension) or break (tensioned).
There is no such thing as a perfectly build wheel, all wheels need some work over time unless they don't get much use, ie not stressed. A road wheel is not stressed much in contrast to a muni wheel, so you should expect more or less truing depending on how you use your wheel.
You can use thread lock when building a wheel, this will make detensioning less likely, but even threads with thread lock can move over time. I build my own wheels, I use thread prep, but not thread lock. I true my wheels every six months or so unless I do something dumb and mess up the wheel
When a wheel is built or re-trued, the spokes can twist vs tightening in the nipple, so when you ride the wheel you can hear the spoke detwist when it "pings". Generally, the twisted spokes are relieved by the builder/truer while they work, but sometimes they forget a step or they miss one.
When the spokes detension while riding, this generally means your wheel is going to come out of true, but it may not be enough to make a difference. Spin the wheel and see if it's true.
This might be a good point at which to learn how to true your own wheels.