I had a guy approach me today while flying at a state park insisting what I was doing was illegal and threatening to call the park police. I had previously done quite a bit of research and found some restrictions in some state parks in NY that require permits but not the one I was at. The parks website had a long list of restrictions but nothing on the subject of any hobby aircraft. He was pretty persistent and insisting he would call the police even though I was quite certain I was right. It shook me up and after he walked away I didn't want to be distracted and crash or something so I landed and left. Has anyone experienced something like this? What is he best way to be prepared for a challenge about legality from a stranger?