UPS tracking mentioned there was a mechanical delay in KY which would result in delivery one business day later (9/22).
09/21/2016 2:09 A.M. A mechanical failure has delayed delivery. We're adjusting plans to deliver your package as quickly as possible. / Your delivery has been rescheduled for the next business day.
At the top of my tracking page, it still says delivery is still on time for today (9/21) however.
Scheduled Delivery:
Wednesday, 09/21/2016, By End of Day
To try and gain some clarity, I chatted with a UPS rep:
Carlos C.: I would recommend if you can wait at least until 10:00AM please and check if we have any additional information, and no, sometimes they do not scan the package to avoid any additional delays, however since they have not changed the delivery date for tomorrow, you can still expect the delivery for today.