Tell us how you planted it. This is a good time of year to get trees on sale, but you have to be careful not to plant them too deep, and you need to soak them before planting and be sure there isn't extra dirt in the pot above the natural root flare. About root flaresTree planting video
from 2008 - Howard does a lot more regarding unwrapping the roots and these days he almost bare roots them (even when they come from a pot).
If you didn't soak it to avoid the edge of the dirt from the pot acting like a barrier to water, and knock out some of that dirt and (carefully) pull roots out from the tree and spread them in the hole you dig, you can end up with circling and girdling roots or a tree that won't get enough water. If you didn't plant it properly, you can redo it.