Spurious tar or amrestore error (I hope).

On the last two runs, the regular amverify pass over amanda's tape has
thrown up this type of error - which is repeated for the same filesystem
if I re-run amverify. This is from the second day it happened.

Tapes:  byerhope23
Errors found: 
byerhope23 (byerhope._dev_sdk3.20030501.0):
amrestore: WARNING: not at start of tape, file numbers will be offset
amrestore:   0: restoring byerhope._dev_sdk3.20030501.0
/bin/gtar: Skipping to next header
/bin/gtar: Skipping to next header
/bin/gtar: Skipping to next header
/bin/gtar: Error exit delayed from previous errors
64+0 records in
64+0 records out

The first time this occurred I assumed that there had been an error on
the tape, so I forced a level 0 dump of that filesystem and all
subsequent filesystems on that tape (it was near the end). The SAME
FILESYSTEM came up which the same error on the following day - this time
using a new tape. After this happened, I re-read this tape by hand
(using just "mt fsf" and "dd" and was able to extract the entire
compressed level 0 dump into our holding partition. gzip -d and tar are
able to extract the list of files, so the tar file itself seems good
when obtained in this way. Is something known to be broken here?

Versions in use:        tar (GNU tar) 1.13.25
                        amanda 2.4.2p2

Chris Ritson (Computing Officer)

Rm 618, Claremont Bridge,       EMAIL: C.R.Ritson AT newcastle.ac DOT uk
School of Computing Science,    PHONE: +44 191 222 8175
University of Newcastle,        FAX  : +44 191 222 8232
Newcastle on Tyne, UK NE1 7RU.  http://www.cs.ncl.ac.uk/~c.r.ritson/