I've seen this before. I've made purchases from Europe and Asia for shipment here in the US. Sometimes I get them within the specified delivery time, but other times there is a delay on the US side for some reason.

Once I made a purchase from an online shave store in Turkey. The store had to send 2 separate packages (via local postal service) within 2 days apart due to back-ordered items. I tracked the packages online. The last package that they mailed was the first one I received, on time. The first package that they mailed was delayed on the US side (in Flushing, NY to be exact); I didn't get that package until 2 weeks later.

International postal service is weird like that.