List search broken?

List search isn't returning some messages I'd expect it to.  For
example, if I use Advanced Search to search for "infinity" in all
mailing lists and sort by date, I don't see either of the following
messages, which do contain the word "infinity":

http://archives.postgresql.org/pgsql-general/2006-02/msg00848.php
http://archives.postgresql.org/pgsql-hackers/2006-02/msg00919.php

Is something amiss?

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Michael Fuhr