BBC: Genesis 3:8
And they heard the sound of the Lord God walking in the garden in the cool of the day, and the man and his wife hid themselves from the presence of the Lord God among the trees of the garden. - Genesis 3:8
I would argue that this in fact is the first clear Christophany in the Scriptures. Christ Himself is clear that no one has seen God (John 1:18) and taken literally this would seem to contradict the idea that the Lord God described here is the Father.
To be of note are the many material elements within this verse. Our Lord God is "heard" and perceived as "walking". Adam and Eve had finished sewing clothes for themselves (Gen 3:7) and God has come down in the "cool of the day". It can be seen that Adam and Eve recognized the signs of God's presence. They were familiar with Him and His purpose for being in the Garden.
It is not simply that Adam and Eve hid. They hid knowing God desired to be among them. To assume such an encounter between creation and the Creator had occurred before is permissible. They knew His intent in His visitation and they attempted to thwart His will. More completely now we understand why John would say "His own did not receive Him" (John 1:11). For God still reaches to man and man knowing God's intent hides (John 3:19-20; Rom 1:19, 21).
*The Bible Blogging Commentary is a slow and simple treading of the Scriptures. No quotes from other theologians and no explicit Greek/Hebrew lessons.*