I'm not going to pretend and attempt to decipher your experience. It would be arrogant and presumptuous of me to explain what you saw.
My only observation would be the following. It sounds like your meditative technique consistently takes you to place more akin to lucid dreaming
rather than a "typical" meditative state. In my personal experience when I meditate, it takes me to a place of no mind, and in that state I lose my
interpretive sensory relationship to myself.
If you are lucid dreaming, just like regular dreaming, you sometimes wake up and can't shake the emotional imprint of the dream for the rest of the
day. Also lucid dreaming can be highly suggestible from one's subconscious. So if you have specific fears or interests, they are likely to surface
in that state.
However, if you feel that you were in a true meditative state when you had this most recent experience, it might mean that something is trying to make
itself known to you when you are open and perhaps less protected. In that case I would suggest that should this presence reappear, the best thing to
do is to confront/engage it. At the very least you will be able to identify it's nature.
It is in the Zen tradition that life will always bring you exactly what you need. Perhaps this is just a personal hurdle for you to overcome.
Having said all that, it could also be bad sushi!