Are there instances from the Hindu mythology wherein Gods have met their incarnations?
Yes, the eighty-ninth chapter of the tenth canto of the Srimad Bhagavatam mentions a story where Shree Krishna meets Sriman Narayana, along with Arjuna:
Lord Kṛṣṇa offered homage to Himself in this boundless form, and Arjuna, astonished at the sight of Lord Mahā-Viṣṇu, bowed down as well. Then, as the two of them stood before Him with joined palms, the almighty Mahā-Viṣṇu, supreme master of all rulers of the universe, smiled and spoke to them in a voice full of solemn authority. (Srimad Bhagavatam 10.89.57)
You can read the complete story here.