I frankly think it sounds like he was just taking a wide-open opportunity to BS you. There's not really any such thing as a junior cop. You're either a cop employed by a department or you're not. And no so-called junior cop has any authority to wiretap you. Even regular cops or federal agents generallly require a federal warrant to do wiretaps. You've not really even done anything to arouse suspicion.

Think about it. Seriously. You're a young person. You're making a deal valued at $30. There are bigger fish to fry when it comes to drug crimes than you. Like real dealers. Any real cops are going to use their limited resources to go after someone who's buying and selling a lot more drugs than you are. Most of them currently care a lot more about meth than they do pot. Sure, they'll arrest you if they see you with weed because it's their job to do so, but frankly they're not going to waste their time on you or believe any heresay they got from some other younster.

I'd bet money that this guy was truly just jerking you around because he knew you'd fall for his story and panic. Steer clear of him in any business dealings in the future. You don't need the aggravation. If you're still panicked even after reading this and are really worried about your future if you make that buy, don't go through with the deal. That is a choice you're making, you know?