Yeah...I order everything XTC/King Crimson/Jethro Tull related from them, too. This was the first time I've ever had an issue.
It won't stop me from ordering from them again.
It was pretty obvious that the barcode on the shipping label was causing issues with shipping - and while they seemed to think that it could be the reason - they seemed quite peeved that I mentioned that maybe the barcode shouldn't be on it - as it is only their in-house ordering number.
Nothing else on the package could have kept sending it back to DC other than this barcode. I know my local PO makes sure there are no other barcodes on the package when I send something out.