4.1M is rounded to nearest 100k, VGC number is acually ~4.13M, and while, given the demand, Sony is correct to consider all the shipped virtually sold through too, 70k is both acceptable as uncertainty, error or rough estimate of units still in the distribution channel. Wholesalers and big chains have their main warehouses, and they won't empty them instantly, as soon as a shipment arrives. Xmas week BTW was slower than the previous biggest ones, and the days immediately after Xmas (or after Boxing Day in some countries) surely are the main responsible for this minor slowdown, so less than 100k WW in the channel isn't excessive.
BTW, before the adjustment, VGC total for PS4 was a few tens k over 3.9M, less than 300k error, quite good in a frantic period like two console launches+BF+Xmas.