Then Solomon woke up and realized it had been a dream. He returned to Jerusalem and stood before the Ark of the Lord’s Covenant, where he sacrificed burnt offerings and peace offerings. Then he invited all his officials to a great banquet. [1 Kings 3.15]
I suppose since Solomon was King of Israel that it makes sense that this dream would be recorded for us to know.
However, we must remain aware that this was, in fact, a dream. It took place in the privacy of Solomon's place for sleep - no doubt, one of the most private places in the kingdom.
And, on top of this event taking place in one of, if not 'the', most private places in the kingdom of Israel (Solomon's sleeping quarters), it was furthermore an occurrence that took place in the most private of human places - the mind.
And still, this event was even further removed from public view because it did not occur in Solomon's consciousness - he was not even awake!
There was no formal public announcement of the promise made to Solomon - it was made in the most intimate and private setting possible - a dream. Even with all the distance between Solomon's dream and its public reality however, Solomon indeed became the wisest and richest king of all time.
What could God say to me in a dream?
Father, I so want to be closer to You. I want to be so close to You that even my dreams would be a place where You communicate with me.