When one of my packages got stuck in limbo, my postmaster called the last p.o. on the tracking info to ask about it. It was on it's way after that...
The last I Spy swap I mailed in (priority) ended up sitting at one of the p.o. s on the way for two weeks, before moving on. No explanation, nothing wrong with the package or address. It could have gone to China and back faster! And that was priority--two day shipping!