md5 and trust and pg_hba.conf

Hi,

Question on pg_hba.conf.  I have these entries:

host    all             psgdba           localhost           trust
host    all             psgdba           127.0.0.1/32            trust
host    all             gd07           localhost                trust
host    all             gd07            127.0.0.1/32           trust


Command to logon to Postgres:
/usr/pgsql-9.3/bin/psql -d postgres

If I am logged on 'gd07'  at the server , it lets me log-on to Postgres without prompting for password
If I am logged on as 'psgdba', it prompts for password.
As you can see, both have 'trust', but 'gd07' is the instance owner.

Why does 'psgdba' prompts?  What I am missing?
Your help would be much appreciated.

Thanks.
Maria