Here we are in the middle of a WI winter with furnaces and wood fires roaring!! What does that do to your walls or more so the plaster/paint, especially in new construction while the house is settling and drying??? These fine, hairline drywall cracks are normal! It happens from the changes in moisture and dryness. A quick paint touch-up will make them disappear and look good as new. If it is more than a hairline crack, then it may need to be touched up with plaster and paint. It’s best to do these repairs after the heating season is over and the expansion and contraction evens out.