missing links error

I am sure this is probably in a FAQ somewhere, but I cannot find it.

I have a list of files I was to put in a star archive, so I do something
like:

star -c list=backuptest-1.txt file=test1.star

which runs to completion, but I get numerous (thousands because I am
writing to
500GB tapes) errors saying something like:

star: Missing links to '/path/to/whatever/file'.

I can go and access the files and they seem proper, so what's with the
warning?  I know I can nix this error with the -l flag, but I want to
make sure I am not missing data.

thanks,

Dan