It is most likely nothing, is my guess. If I were you I would just show up, smile, and be cooperative. Remember, the idiocy that abounds in the court bureaucracy is essentially limitless. Ask me sometime about my lunch date with ATF. I promise it will make you feel better.
where is it listed as subdivision recreation area? in the recorded deed to the 5 acres? is there an HOA of any sort that pays taxes on it? are their any rights to its use or access referred to on your deed or any of your neighbors?
if it was an informal understanding and nothing on record then...