The same happened to almost the same level with weight from the center post. There was virtually no visible shake when the tripod legs were dampned by my weighted fanny pack and straps wrapped around all three legs. I don't use long lenses without as much dampening as I can get. Try it an let me know what you think. It depends a great deal on the camera.
Some models have much better mirror damping than others.
If you have MLU, then the best bet is to run tests with the equipment you use and see where it makes a difference. Adding weight to the tripod, or damping the legs can't hurt and can only help. It's always worth a try. You can then wait for any small vibrations to die out before firing the shutter. He found that you will have the same effect as MLU when you hold your tripod-mounted camera body steady with your hands when you press the shutter.