OK, so the paste isn't nonstaining anymore - big deal. Priming over dust causes poor adhesion . It's generally true that you must clean surfaces of dust. However, last year I discovered in basement testing that different brands of primers handle dust very differently. One primer remained well adhered, while the other just about fell off the sample board.
New houses settle.
Maybe if the house was built on active swampland . Our new houses shrink for a few seasons, and boy, do they shrink. Not too many years ago, builders wouldn't have dared to use the type of moisture-laden studs they use now, because of the nail pops and subsequent lawsuits by new owners. Then the miracle of the sheetrock screw enabled awful lumber to be used with nary a pop at all. What I now see in new construction is that the entire wall shrinks in height, and pulls the tape joints at the ceiling.