There is a bug in the sample view in the psql_replication_check.pl. 
It calculates the age incorrectly, returning the minutes part of the
interval instead of total number of minutes.

The sample is:

CREATE VIEW replication_status AS
SELECT customer_name AS object_name, 
transaction_date, 
date_part('minutes'::text, now() - transaction_date) AS age
FROM customer_orders
ORDER BY id DESC
LIMIT 1;

SELECT  '2005-07-01 07:20:00'::timestamp - '2005-07-01 04:10'
 ?column?
----------
 03:10:00

SELECT date_part('minutes', '2005-07-01 07:20:00'::timestamp -
'2005-07-01 04:10');
 date_part
-----------
        10

Instead of returning the total length (190 minutes), it gives the 10
minutes of 3 hours 10 minutes.

The right solution is use extract the epoch, the length in seconds,
and divide by 60.

SELECT date_part('epoch', '2005-07-01 07:20:00'::timestamp -
'2005-07-01 04:10') / 60 ;
 ?column?
----------
      190

For the example it shoud be:

date_part('epoch'::text, now() - transaction_date) / 60 AS age

 - Ian