Happens on acid and shrooms and other psychedelic drugs as well. slight distortion of how you perceive things. especially within time moreso then the deterioration of the ego, at least when pot is involved. Time dilation though, now that's interesting! Time doesn't exist as you perceive it, it's in actuality an illusion. Time itself is something we've through interaction and relation to this material reality have come to view as to better understand or comprehend the motions and changings of matter itself. Time is just something we use to explain this process be it through science or through practical exposure in day to day life.
It is not unheard of to perceive time differently, it's merely a distortion of the mirage. We take in information through our senses, touch, taste, smell, sight, and hearing. Time is not only a byproduct of this information being processed but when through events, natural or unnatural ( for sake of our conversation drug induced then) the information received is therein processed differently, giving you said distortion or dilation of what we're calling time. The only thing weed can do in a psychedelic sense is cause this shift in perception. I once had an adorable girl tell me in such a convinced manner that marijuana induced psychic hallucinogenic effects. Oh how I laughed, You better not be presuming the same! Or I will have to pinch your cheeks and give you such the talking to. lol. Because it doesn't. Hallucinations don't happen on pot, and psychic abilities do not exist. period.
The reassessment of your issues, giving you clarity while on marijuana I can only assume is a tie with this dilation along with the breakdown of attention on particular thought. What's essentially happening is you're not paying attention to how you'd normally view time, and are focusing on an issue at hand via tunnel vision. With no other thoughts impeding your process, you achieve the illusion of mental clarity, you're either really analytical and you don't know it, or you're just really lucky hitting it on the dime when you do.