Weird right?! Quite often, believe it or not, we will see shipping carriers mark a package as "DELIVERED" in their tracking system, but not actually physically deliver the package for a day or two later. Honestly, we are not sure why this happens as often as it does. It could be due to a variety of factors, to include; no one was home to receive the package, the mailbox was full, the carrier could not locate the address.
If this happens, do not panic. PLEASE contact your local carrier office, not the "1-800" hotline, as they will not be able to assist. Likely the package was brought back to your local carrier's office, and a delivery may be attempted the following day. However, it is always a good idea to contact them to make sure this is the case.