Luke 2:33

And his father and his mother were marveling at the things which were spoken concerning him.

Childers' discerning comment on this catches the truth of it exactly:

Simeon was not telling Joseph and Mary anything they had not previously learned about Jesus. They marvelled, rather, that these truths should come to them from a stranger and under such circumstances. The marvel to them, and to us, is that everything that was said by all of God's messengers harmonized so perfectly.[28]