Same thing happened to me a while back.I just heard back today, a couple days after I sent an email inquiring about an update. Apparently one of my items is on backorder and I have the option of waiting until all backordered items are in stock so it can ship as one package, or I can ship what's in stock now and get the backorder shipped as it arrives at additional expense.
Except that option wasn't made known to me until nearly two weeks later when I reached out to them. I am actually really annoyed by this.