When a ptosis repair is performed, the levator muscle is shortened to improve the lid height. When someone has good levator function, the result is much more predictable, and that is probably what your surgeon was referring to. If you just had the surgery done, there may still be some edema which is weighing down the eyelid. However, if it was several weeks ago and most of the edema is gone, the muscle may not have been shortened sufficiently. You need to see your surgeon to discuss this.