Tire/tube issue

I currently have a set of Bontrager Race Lite tubeless wheels that I am running Bontrager Revolt Super-X tires on, with tubes. I removed the plastic rim strip to run tubeless and replaced with cloth rim strips. For a few months now I have been riding at about 50 psi since some of my riding is streets and then mostly hardpack. Last weekend I get 6 miles from home and I get flats in both tires almost simultaneously. Before the ride I had pumped the tires up to 65 (max for these tires) because I would mainly be on paved trails. When I got home (after being picked up) I took both tires off and found many small, loose granules in each tire. I asssume the higher pressure coupled with the tube being up against these granules gave me a flat in each tire. I had found one tiny hole in each tire, on the outside of the tube, where it contacts the tire, not the rim or rim strip. The tires are almost new and there were no "wear marks" on them, so I have no idea what these granules were and where they came from. They seemed to be rubber, but I am not sure. It almost seemed like something had solidified inside the tire, like maybe the talc that sometimes comes on tubes. I cleaned out the tire and replaced the tubes and good so far. Anyone ever experience this?