I have read that it is possible for genetic material to cross a graft (I have no scientific proof and would assume the tree was a sport) but, if you are certain this is not a grafted tree and instead a seedling, I am going to think in a different direction for awhile.... The newest red foliage and the older green foliage don't appear to be on the same branches and there is no sign that the red was ever green. Bringing me to a new thought - You could have a very unique seedling, a Chimera.
A chimera is a plant (or other organism) that has two sets of DNA. The most common chimera in a plant is one with variegated leaves: The two sets of DNA bump up against each other in one leaf. But another form has different colored foliage or flowers on different branches of one plant. The only one I can think of right now is Toyo Nishiki Quince.
The only way to tell (other than DNA testing) is to give it a couple years and see what develops. If its truly a chimera, it will continue to produce both red leafed branches and green leafed branches. If it was environmental, the tree will be whatever it should be when it leafs out next spring.
Please keep us posted on what happens and with new photos (on this thread).
