Key Press Queuing

I've noticed when I use C# code to move a game object in response to a keypress, that holding the key down for a few seconds nonstop causes the object to continue moving for a moment after I release the key.

Alternatively, if I just jab the keys quickly, the object starts and stops instantly.

Is this some kind of key queuing and can it be disabled?

Here's the basic code I used to do the move (Spuddie is just a sphere with "arms" along it's axes):

public class SpuddieMover : MonoBehaviour 
   public GameObject Spuddie;

    private void Update()
        float z = Input.GetAxis("Vertical");
        if ( z > 0)
            Spuddie.transform.Translate(Spuddie.transform.up * Time.deltaTime);
        else if (z < 0)
            Spuddie.transform.Translate(Spuddie.transform.up * Time.deltaTime * -1);


Thanks in advance for any help! :)

Go to the input manager and change the gravity and sensitivity for the axis as desired.