@Revenant Give them benefit of the doubt......I had a package a while back take a while to get to me that I thought it was lost. Nope, it was just moving very slowly due to the backlog from all the holiday packages

I recently had a Priority Mail - Two Day Delivery package arrive at my local post office.  Tracking confirmed it arrived at the PO on Nov. 14.  When it had not been delivered by Nov. 21, I went to the PO to try to pick it up.  They had a photo of the package when it arrived but could not find it.  It was finally delivered December 12.

I have never had a Priority Mail package lost, but this is the second time one has taken a month to be delivered.  The first one, two years ago, left Houston, showed up in Greensboro the next day, Newark a week later, Miami a week after that and was finally delivered 27 days after shipping.  So, I would say give them a few days and open an lost package ticket with the PO.  It will eventually show up.  

I have had coin packages lost or at least not accounted for for a long time.  Or sent on crazy journeys to different POs around my city being told it was there, no there, no its out for delivery.  Then a couple days later it gets delivered.  Tracking can be right, or wrong.  Something I send out w tracking gets picked up but is not in the system for a week, making it look like I never sent it.  Except for something I returned to Australia, nothing has been totally lost yet, just really delayed.  Also USA customs checked a coin from the UK and I got the envelope opened with no coin in it.  The shipper got their insurance $, I believe, and they gave me a credit.

Check this one out  "ALERT"   https://tools.usps.com/go/TrackConfirmAction?tLabels=RR002220636SM&utm_source=alertxdd&utm_medium=email&utm_content=tracking-number&utm_campaign=trackingnotify

That doesn't look good.  Nice coins in there.  But actually it was in my mailbox about 10 days ago, and all OK.  The post guy must have just forgot to scan it as delivered, or to have the desk sign for it.  I gave him the envelope to scan a couple days later and told him I got it and I hoped there was no problem on his end.  But a week or more later and USPS still shows it as "ALERT Delivery exception"

It could always be worse.  See:

https://coinweek.com/people-in-the-news/crime-and-fraud/numismatic-crime-alerts-coin-dealer-robbed-after-show-stolen-packages/

Thankfully you know your stuff is not hyper-valuable, but these guys have crazy coins out in the mail

I've had over 1200 eBay purchases delivered from all over the world in the past 15 years and to date, only one was actually lost by USPS and never found.  A few have been MIA for a while, but with some intervention, all but that one got delivered to me.

The USPS internal tracking seems to have gotten much better in the last year or two.  I've called my local P.O. and had them track deliveries that seemed to be in limbo like yours.  I also had one that showed online that it had been delivered, just not to me.  They were able to find the item pretty quickly and even called me back to tell me and again to make sure I got it.  They've gotten much more service oriented, at least at my P.O.

You may need to check on you package, but odds are pretty good that you'll get it

Well, I had told myself if I didn't see anything by today (20th) I'd contact the PO. Woke up and checked today and it's in town. It'll probably be delivered today, maybe tomorrow. I guess they did okay this time.