Extension prevents dumping table?

With PostGIS 2.0 if I load/install postgis using the command:

create extension postgis schema postgis;

And then use the command:

pg_dump -t postgis.spatial_ref_sys dbname > spatial_ref_sys.sql

I get an output that contains a few "set" statements, but no table
definition or data from the table.

However, if I install the PostGIS components the "old" way (not using
the extension loader), the pg_dump of the table works just fine.

Any ideas how to fix this or why this happens?

thanks

chander