I'm just wondering if that isn't a different tree than I'm used to. Here, you have a stem grafted to roots and top grafted to stem and the nice smooth bark of the stem falls away as the tree matures. If you stack the mulch a little higher (1 foot), the stem puts out roots and you end up with a standard size tree instead of a dwarf size tree by defeating the root graft. Got to love those mulch it high guys, who teaches them the stack the mulch high against the tree theory of mulching? Could this be a case of bury the roots well below ground level system of planting? The only thing missing from this tree are the sticks tied to it to hold it up strait with the wire ties grown into the bark. The tree looks okay but I agree with Trig, rake some of that mulch away from the base of the tree. Be gentle about it and don't be surprised if the next crew has it stacked back up against the tree with the next round of mulching. There is a guy here that likes the Volcano mulch system where the mulch looks like a volcano with a tree coming out the top. 2'-3' feet of mulch against the tree and steep taper away from the tree with colored (dyed red) mulch. You can tell every job he does by the red volcanos in the lawns of his customers. Back to your tree, are we seeing a root graft in the pics?