Data In Tables Sometimes Have +

I've noticed as I interact with my database I use for customers, there
are from time to time values that have a strange '+' character. For
example:

forge=# SELECT cust_id, cust_name, cust_contact, cust_email
FROM customers
WHERE cust_name Like 'Truth%';
  cust_id   |     cust_name      | cust_contact  |     cust_email
------------+--------------------+---------------+---------------------
 1020105577 | Truth Custom Drums | Geoff Barrios | info@truthdrums.com+
            |                    |               |
(1 row)

You can see the field called 'cust_email' shows a trailing '+' for
some odd reason. Generally I would chalk this up to fat fingering data
or something but I have seen it on more than a few occasions and
really don't know what it means or why it's there. I know if I use the
'UPDATE' statement and change the address, it goes away:

forge=# UPDATE customers
forge-# SET cust_email = 'info@truthdrums.com'
forge-# WHERE cust_id = '1020105577';
UPDATE 1

Now the '+' is obviously gone...

forge=# SELECT cust_id, cust_name, cust_contact, cust_email
FROM customers
WHERE cust_name Like 'Truth%';
  cust_id   |     cust_name      | cust_contact  |     cust_email
------------+--------------------+---------------+---------------------
 1000000007 | Truth Custom Drums | Geoff Barrios | info@truthdrums.com
(1 row)