We process numerous orders each day, while this is no excuse, regrettably backorders do happen. There are two most likely reasons for this:
1. If the quantity of the item you selected is low and multiple orders come in for the same item exceeding our current stock, then a backorder will occur.
2. Our inventory levels do not match our actual inventory levels in the warehouse. Although this is a rare occurrence, sometimes it could happen. For example, if our system indicates one item with 10 units in stock and you order 10 we should have enough to fill your order, but suppose when the order is actually pulled to be shipped, our warehouse team discovers the wrong amount is actually available, a backorder will then occur. We will ship your other items (with your approval) now and when the back-ordered item is available it will ship to you.