I did hear on the way back home this morning a slight "twang"...
Any ideas what it may have been? not been on a bike for 35 years and collected the bike a week ago...
It would have been a spoke untwisting - when the spokes are tight, and the nipple is turned during truing, it tends to twist the spoke round with it rather than the nipple turning on the spoke threads. Then, when you ride, the spoke goes a little slacker as it passes round the bottom of the wheel, and the friction between nipple and wheel rim is no longer enough to stop the spoke untwisting, which it does, with associated twanging noise.
Sometimes normal riding is enough and you get a fair few twanging noises for the first 50 yards, sometimes the spokes are tighter and it doesn't happen until you hit a pothole, or add a bit of sideways push by getting out of the saddle and honking.
A good wheelbuilder will untwist the spokes as part of the build process, usually by lying the wheel down flat and pushing down on opposite sides of the rim. They should also stress relieve the wheel by squeezing pairs of spokes together hard (gloves usually required), which fends off broken spokes later in the wheel's life.
However, with the factory wheels on new bikes, this often doesn't happen.
It's usually a good idea to work out what a noise is caused by before you start ignoring it. Sometimes a noise can be the warning before the failure that causes a nasty crash, such as creaks before a handlebar breaking.