I got 2 books in the mail today and both of the senders used electronic postage so it included the DC.  On the packages though someone had "cut" both of the bar codes off with a pen.  One of the books was PBS postage so I can see that it was scanned in my town before it was delivered.  On the other one I can't read the number under the bar code to see if it was scanned or not. 

Is there some reason that the PO is doing this?  Or do I need to be worried that my mail is being tampered with?  The packages were only in the box for maybe an hour before I picked them up and I have never had any problems before...

Mine come like that all the time, I guess it is way my PO does the cancellation on the printed postage. Probably a way to prevent anyone from reusing the barcode. They also date stamp cancel every stamp on books that come with stamps on them. Whoever does the sort at my PO is very thorough.

They were both mailed media rate. 

I guess if others have books appear that way I won't worry about it.  It just struck me as strange, but maybe my PO is trying out new procedures.