I think that it is the quality of the paper & fiber strength. I've notice over the last several that you get the dust more and more also. We have become accustomed to doing a back trim on almost every thing or plan out the cutting better to allow the finish edge to always be inside the cutter. You can chase your tail with blade sharpening, bevels & dual edges, without any difference to the finish cut.
I think you may be right. Today we had some hotter and more humid weather and I had a job sitting out for a couple of days, printed but waiting to be cut. I noticed the dust seemed to be reduced. I think I may have to try and order a few different types of stock to experiment.