I was checking on the progress of some books I shipped out using PBS labels as part of my book clearing project, and a number of them have a "mis-shipped" line entry in them.  What does that mean, and why would PBS labels (with PBS postage) be generating such an entry?  It makes me concerned that there is some kind of issue with the address or postage.  Has anyone else seen this?

It likely got put in the wrong bin and ended up at the wrong processing center. It will get rerouted back where it should have gone.

Most of the scanning that happens at the post office is done be humans. They make mistakes like the rest of us.

Just so odd to get a bunch of those messages on multiple books - but maybe they were all handled by the same human!

post office problem. Not a PBS issue.

If they all happened around the same time in the same city, then somebody just put a bin of packages on the wrong truck. Maybe your books were supposed to go to, say, St Louis where they would get split up and sent off in different directions, but someone at your local P.O. made a mistake and put them on a truck to Pittsburgh. When the workers (or machines) in Pitt find them, they figure out that these packages are in the wrong city, so they record the mis-shipment and then send them on to the right place. It might add a day or two to the delivery time, but they'll get where they're going.