I'd take a guitar pick (or my fingernail- but I feel like a guitar pick is more consistent) and pluck each spoke when you get the wheels and listen for them to be pretty close in tone. If they aren't, then keep your eye on the wheel for trueness- it'll likely start to go out,
then, as sugges
Andy_K above, take it to the LBS for touch-up. If the tones are all pretty close, you may be lucky and ride indefinitely without needing the LBS!