A new introduction of the big leaf maple, grows eight feet tall by four feet in ten years. Picture taken 5/15/05
The grower that selected it in the 1990's told me those size dimensions. It is a dwarf var., i trust him, he is an extreamly well respected grower.
One I bought recently has even longer internodes than yours. Looks like a regular bigleaf maple seedling, except for the color. Seedling rootstocks impart vigor that original seedling mutations may lack, this has long been a problem with the production of dwarf and slow-growing conifers. A small, dense bush that arises as a seedling takes off and grows out of character when grafted onto a seedling rootstock with normal vigor.