It sure does look like a graft or bud union where the grower t budded scion wood onto different rootstock.
Then the spring of the following year the top of the budstock is cut off just above the t bud and the new bud is trained to grow straight. The wound usually grows over the first year.
Or it could be where the grower had a crooked seedling and cut the plant off low early in the spring this forces a new bud to emerge and the 2-3 year rootstock forces up a nice straight top. The bark does look like a red maple.
The wound should not be covered and should fully heal this season.