pg_dump, no inserts but \copy?

I remember the pg_dump command creating dumps with \copy in them
But for some reason (upgrade of postgresql?) it now started to
create dumps with inserts, as though I gave it the --inserts
argument (but I don't).

man pg_dump explains how to make it use inserts, but I cannot find
anywhere how to make it create \copy dumps.

Postgresql version: 7.2.1

Thanks,
joostje