"Yes, you should move it if it is right up by the house. As a general rule of thumb, a tree such as a redbud (mature size over 25 feet) should be 15 feet from a structure.
The best time to move it is when it is still dormant. That way it won't lose as much moisture through the ordeal (remember, you're removing roots, so it won't be able to fend for itself as easily).
Since it has already leafed out, I would root prune the tree this year and transplant it this fall after the leaves haved dropped. Root pruning means digging around the tree (about where the canopy ends) and severing the outside roots. This will cause the tree to grow more roots closer to the stem, helping it to succeed when you transplant it this fall.
Luke Miller, editor
Garden Ideas & Outdoor Living magazine"