Maybe you could add a screenshot of the exact location or at least zone, x and z coordinates so that Xsyon can check it in more detail?
When I scavenged or foraged and log out, then login even a day later at the same location, I also get the message that I scavenged/foraged here already. But this happens everywhere, not in a single spot. Looks like the system remembers me doing something, but is not comparing with the time of last action.