I got a PM from another member today that said this:

Jennifer - the 2 books i sent to you came back to me today as "undeliverable, unable to forward" and there was a marking on them that said "NSA" which the mail man told me means no such address. the addres they were sent to was the one on the PBS label -

I checked the address, and it's correct. If I remember correctly, I've gotten a couple of other books where the sender used the PBS label, and they were delivered fine. What do I do?

Jennifer, I would talk to someone at your local post office.  As for the books that you didn't get, the other member can see if her post office will remail them since the address is correct.

Hope you can get it worked out!

I went to my local PO today and the clerk was REALLY nice. She said that my street is on 2 different routes (it has 2 parts -- the Houston area is full of split roads because of the bayous), and the mail must have gotten mis-sorted. We apparently have several new carriers, and she said that probably instead of throwing the package back in the bin to be re-sorted, they sent it back as NSA. She also said that the sender shouldn't have to pay any additional postage, just take it back to the PO and explain to them what happened. Yay for nice postal clerks!

Thanks for the replies!