You might have some other entry that is taking precedence.
Command to logon to Postgres:
/usr/pgsql-9.3/bin/psql -d postgres
If you don't have PGHOST set then most likely you are not going over a tcp connection (which is what host entries in pg_hba are used for). Instead the local entries of pg_hba are taking effect.
If I am logged on ‘gd07’ at the server , it lets me log-on to Postgres without prompting for password
do you have a *.pgpass* file in the home directory?
If I am logged on as ‘psgdba’, it prompts for password.
As you can see, both have ‘trust’, but ‘gd07’ is the instance owner.