It is not wrong or bad, but I think it is going in the opposite direction from trust; taking something from someone without their knowledge and using it in a self-absorbed way. That kind of comfort comes with a price you may not want. You are not learning to trust yourself and practice learning your own self-soothing skills (babies have to be left to cry before sleep so they can learn to make the transition into sleep by themselves) and you are collaborating with the dangerous twin fantasies that you can have T anytime you want and that T is her voice.