I have had a couple of "troubling" things since I started with MMJ... but, I do understand them.
When I use MMJ, my anxiety level drops, and so do my "filters" and blocks. When the MMJ wears off, I might feel angry or upset. Not usually, but if something has surfaced.
This is very, very similar to the effects of an extended meditation session - I have done a few 10-day Vipassana meditation retreats - where old, mostly forgotten trauma can silently make its way to the surface. A couple of times, I had old anger rise up, blow up, and then just melt away. In Vipassana, the phrase "it arises, and passes away" is used in the teachings, constantly.
I try to keep in mind that it will arise, then pass away.