This happens when items are added to the cart, but a valid shipping destination hasn't been provided yet. The system assumes that order will meet the default free shipping limit of $70, and since it does not know the actual shipping address it is unable to determine an accurate shipping cost.
Our shipping costs are based upon weight and shipping destination (city and zip code). Once this information is provided and system is able to determine the shipping costs, it is updated accordingly.
Please keep in mind we offer free shipping on all orders over $70. Further, this limit applies to ALL of the products on our site.