pg_dump : problem with grant on table columns

Hello,

I sometimes define some access rights on table columns instead of whole
table. Everything works fine except when I perform a dump.

When I dump a databse that contains such access rights, the pg_dump utility
generates commands like this one :
GRANT SELECT("Login") ON TABLE "Clients" TO "AgendaSubscript";

But, when I execute the content of this dump in a fresh database (for
backup and restore stuff), those commands are rejected and thus, my
restored database has not the proper access rights.

Is this a bug with the pg_dump tool or am I doing something wrong ?

Regards,

Brice André