I'm convinced that because of the government shutdown, USPS tracking and deliveries are incredibly unreliable. I encountered a very similar issue to yours (my sister was sending me something) - the tracking arrived in town. At 7:30am, it said it was out for delivery. At 7:59am, it said that they were unable to deliver the package and that it was held at the post office "per customer request."

USPS usually delivers my packages around noon (or much later), so I know they haven't tried to deliver the package <I>that</I> quickly. Next, there were no pink slips left at my mailbox.

I also have not received ANY mail since the shutdown. Granted, my aunt and uncle have left the country for a couple of months about the same time as the shutdown so they could've placed a mail hold, but I highly doubt it since they've done it for years and have never went for that option.

I'm afraid we'll just have to sit tight and hope things get sorted out quickly.