Before today, every time I revisited the same location in the same hotspots, the rocks were untouched (refilled). During my last run today, I seemed to be finding a lot of depleted rocks. I normally find one or two when I lose my sense of direction and go back over the same ground, but this time I was finding several runs of depleted rocks, and I'm pretty sure that I had only moved forward. Did anybody else notice anything like that?