Glad you were let go. Simply admitting you were smoking without evidence means nothing. They can't force you into a test unless they find evidence or possession. You actually screwed yourself by admitting anything but understandable in the (stoned) panic. In the future just don't say anything and insist you weren't doing anything wrong, and if they push it scream LAWYER. In most cases unless they think you are big-time or have a history with the cops, they will just let you go on your way without real evidence.

Good you got off. And yeah dude, stay outta parks. NJ ain't the netherlands. We've got some of the most fucked up tough laws in the country.