Hello.
It is common for stepper motors to make noises while they are stepping, but I am not sure if what you are hearing is reasonable or not. Can you post a video so I can listen to what you are hearing?
Hearing more noise as the stepper motor begins to turn makes me suspect that you are commanding steps a little quicker than the stepper motor can keep up. If you ramp up to your desired speed, do you notice a difference in sound?
-Jon