Happens to me pretty regularly when Amazon ships via UPS and then the local delivery (also to my workplace) is handed off to USPS. (You can see the transfer to USPS if you track the package via the UPS tracking site.) The USPS delivery always arrives on the day after I get the delivery notification e-mail. That's also the day after Amazon promises it will be delivered, effectively making Prime a 3-day service instead of a 2-day service. Articles shipped all the way via UPS usually arrive as promised after two days.