I'm going to assume that you're not the puppetmaster. For the time being, I'm going to assume that this is indeed a grassroots ARG, and that you are being contacted by a would-be puppetmaster.
In this case, no, he's not trying to mess with your head. In fact, you're doing what the puppetmaster wants: spreading the word. 4chan has an untapped potential for trailheads. I'm sure he didn't expect this to be posted on 4chan, though.
ARG rule #1: A whisper is louder than a shout.
OP, do me a favor. Head to Unforums, News and Rumours section. You don't need to register. You're going to see a thread near the top that says: "Could that email or IM be a trailhead, or SPAM?". Post everything there, e-mail address, screencap, and all.