A couple of newish cachers found the geocache on the 12th of January and there's a good chance they took the geocoin. They probably don't know how to visit the trackables page and to log it. If I were you I'd send them a nice email explaining a bit about geocoins and travelbugs and ask them to find another cache to put it in or give it to a geocacher friend to do it before it gets lost and forgotten.