Yes! I understand about state parks ,but I wasn't near a park, in front of hotels and have done it before.
Well I hate to say this lay385, but ...... sometimes you just gotta avoid singular busy-bodies, in the future. I too have been hassled at times over the years, at places I felt there was no specific rule or law. Who knows? maybe someone thought you were harming sandcrabs so they called a ranger? Maybe it was just a single ranger having a bad day? etc... In those cases, I've just given lip service, and then in the future, made sure to avoid that ranger's shift. Or come back month's later, and I bet they've forgotten you, or the ranger has moved on, etc... This is, of course, if there's no specific law or rule. Because even if I'm wrong, and you have the exact same guy in the future, with photo-memory-recall, who attempts give you further hassle for not having abided by his earlier booting, then you merely (this time) say that you've checked the rules, and found no prohibitions. He's welcome to correct you, or make a "policy" based on something he morphs to apply to you, if he wants. You can never stop that. Because let's face it: authorities in the field are given latitude to apply laws as they see fit, to fit a myriad of circumstances as may arise in the field.
For example: If there is a law that says "no nudity" on the beach. So lay385 goes out there with a single sock on. When the ranger tries to boot you, you say "but officer, I wasn't technically nude, since I had one sock on". You can see why law enforcement grants liberal powers of interpretation, to field officers, to interpret/morph things to fit/apply to a myriad of circumstances. So what I'm saying is, there really doesn't have to be a specific rule against metal detecting. If some officer/ranger was anal enough, they could just say you're "disturbing the peace" or something. There is simply no way to pre-empt this ahead of time. If this potential bothers an md'r, then perhaps they've chosen the wrong hobby. Ie.: like driving: sometimes, despite your best driving skills, there's going to be another motorist who's going to flip you off (because he thinks you did a sloppy lane change or whatever). So sometimes you have to be a little discreet, know how to give lip service, avoid busy-bodies, etc....