Will I be charged after shipping fee update in after?

Due to improvement of the packaging or Postal Service, the postage may vary on different batch. We will proceed as below examples if the shipping fee difference on prepaid orders.
Example 1: US$10.00 on order. After weight apply, the correct shipping fee should be US$15.00. Difference of US$5.00 will need to be collected, we will send you payment request for postage.
Example 2: US$20.00 on order. Shipping fee updated as US$15.00 when stock arrived. We will refund the difference US$5.00 by cash coupon after shipment notice.
 
Products without shipping fee means postage is only available after first arrival. We will update the postage and then sending Postage Request.