Perhaps it is posted on the navicache.com site. It is not as popular as geocaching.com but sometimes caches appear there that cannot be posted on GC.com
I have some counselors at the campground I work at that are very insistive that there is a cache placed on a nice scenic overlook on a hill nearby. They describe it and it sounds like a real cache, but it isn't listed, not even for premium members only, so I don't know what it's doing there. Guess there are caches everywhere, even where they are aren't supposed to be.