Justin...
I often times get paranoid when i smoke and have cut back because of that, however there was one instance that i smoked and felt the most positive feeling of my life! Lucky for me that feeling lasted a few weeks, possibly even over a month.
So i know where your coming from with this high lasting so long.
Personally, i feel like it's all in your head..Since your experiencing paranoia you may be over stressing yourself. Maybe your environment wasnt enjoyable at the time?
Just let the thought of that joint go...remember, marijuana only stays in your system for 3-30 days. After that..it's without a doubt all in your mind.
Good luck with conquering this feeling.