My parents live on a farm so during the dusty, dusty summers dirt and rain accumulate in the tree and little cedar has survived.
My dad tells me that red cedar tree seeds will not germinate on their own-but must be eaten by birds in order to soften up enough to sprout.
This easily answers the question of how the little tree seed made it into the maple tree's nook as this is one tree on the farm that no one parks their car under!