if !grounded

Hey! Im using this script for my character movement using UnityEngine; using System.Collections;

 public class Controller : MonoBehaviour {
     public float speed = 6.0F;
     public float jumpSpeed = 8.0F;
     public float gravity = 20.0F;
     private Vector3 moveDirection = Vector3.zero;
     public GameObject target;
     private Transform myTransform;
     
     //Animations
     //public AnimationClip Run;
     public AnimationClip Takeoff;
     public AnimationClip Jump;
     public AnimationClip Idle;
     public float jumpAnimationSpeed;
     public float walkAnimationSpeed;
     
     void Start(){
         myTransform = transform;
         animation["Jump"].layer=1;
     }
         
     void Update() {
         CharacterController controller = GetComponent<CharacterController>();
         if (controller.isGrounded) {
             
             
             
             
             moveDirection = new Vector3( 0, 0, Input.GetAxis("Horizontal"));
             //moveDirection = transform.TransformDirection(moveDirection);
             moveDirection *= speed;
             if (Input.GetAxis("Horizontal") > .02f)
             {
                 animation.CrossFade("Run");
             }
             else if (Input.GetAxis("Horizontal") < -.02f)
             {
                 animation.Play("Run");
             }
            else
             {
                 animation.Play ("Idle");
             }
             
             
             
         
            
             
             
              if (Input.GetButton("Jump"))
         {
        moveDirection.y = jumpSpeed;
        animation.Play("Jump");
             }
             
         }    
                 if (Input.GetMouseButton(1))        
     {
                 Debug.Log (" Im clicking fire2");    
                    moveDirection = new Vector3( 0, 5, 0);
                 if (controller.isGrounded)     
             animation.Play("Takeoff");
             }
            if (!controller.isGrounded)
             animation.Play ("JumpStand");
             
    
    
      
     
             
          
        
         if(target) {
             myTransform.LookAt(target.transform);
             myTransform.localEulerAngles = new Vector3(0,myTransform.localEulerAngles.y, 0);
             
         }
         
         
         
         moveDirection.y -= gravity * Time.deltaTime;
         controller.Move(moveDirection * Time.deltaTime);
     }
 }
 
 

and what Im having problem with is this part if (!controller.isGrounded) animation.Play ("JumpStand");

Because the character sometimes can accidently get a tiny bit up in the air when Im going downstairs and that activates the JumpStand animation and brakes the walk animation, I was wondering if I somehow can activate " if (!conroller.isGrounded) " if Im above the ground by a tiny bit? and not instantly. Like " if the character is above the ground by 0.5 or more on the Y axis animatin.Play ("JumpStand")