Ok so I decided with all the problems with the PBS DC that for my current shipment I would try PBS printable postage.  I am a gold key member and this is the first time I've used it so it gave me the .50c fee for free.  I was charged 2.53 which is the media mail rate for a books under a pound.  My question is how will usps know I wasn't supposed to be charged for the .20 for the DC?  Am I over thinking this.  I just want to make sure there won't be a postage due for the reciever. 

I wrapped and weighted the book so I know that amount I entered was correct.  I'm just confused on the waving of the fee and how that works when its scanned or checked at usps.   

All the info the USPS needs about the postage and delivery confirmation you paid is in the bar code, and the PBS postage bar codes are scanning just fine.  (I sent out about 15 packages this week.)  As long as you verified the weight of your book (or your wrapped book) and entered that info on the Print Wrapper page, you should have no worries.  If you forgot to weigh your book and enter the info, you are probably okay.  The PBS estimated weight is usually right, just not always.

Just guessing here Elizabeth, but the 'prepaid' postage part is probably the USPS clue regarding the DC charge (or lack thereof).  Yes, you're over thinking it, the software programs USPS approves should handle the details.  If your package weight is correct, Blue Box without stress!

LOL Yeah I figured it was me over thinking this but I just wanted to make sure.  Thanks Guys!

With electronic postage, the DC barcode won't print on the package unless it's paid for. As long as your weight is correct, it should all be fine.