I doubt the umbilical moved the rocket. What you were seeing was probably the effect of wind -- it's a very tall, narrow structure with a big fairing on top. On

I doubt the umbilical moved the rocket. What you were seeing was probably the effect of wind -- it's a very tall, narrow structure with a big fairing on top. Once the clamp is released, it's only held down at the bottom, so like any tall building it flexes noticeably in the wind.