when I left the house at noon that day, the new mailbox was not firmly fastened, as if the landlord (or whoever intalled it) didn’t quite finish and had to leave in a hurry. However, when I came back home that night, the mailbox was firmly fastened and all the screws looked tight.
Sounds like a second trip to Home Depot to get the rest of the things to finish the job. Used to happen to me all the time, but it was usually three trips per job.