Shipping Issue / Question

I ordered two items, different sizes and colors, from the same company. They were shipped via USPS, and both were marked delivered today. Unfortunately only one of them was in my mailbox. I called the post office, but since its the same day I cant even file a report to track it bc you have to wait 24 hours. So I will call and do that Monday. questions is... has anyone experienced similar that can give advice on how to navigate this? Its a $25 item, so not a huge loss, but I dont want to tie up that slot for weeks on end either. I was thinking I will call and file a report, hope it gets found and (re?)delivered and wait maybe a week or so, and if no resolution.. just review it based on the quality of the item I did receive? Should I bother contacting the merchant?

FWIW, the item was a Jacobite shirt (dont want to link it but searching that name will find it easily enough) to go with the kilts I ordered... and for the record, it runs a bit small but omg the quality of this fabric is phenomenal. Dense and yet very soft.. the cut is very basic, not fitted at all of course, which hubby will have to get used to, but the quality was really impressive.