PostgreSQL 9.3 - pg_stat_database - tup_returned got "too high" value

Hello,

I've got a "problem" with stats at PostgreSQL 9.3. Problem can coupe(?)
sources:
a) I do not understand what values should tup_returned contain
b) tup_returned contains something else than can be understood by reading
official docs
c) something is wrong with our database "server"

According to docs (
http://www.postgresql.org/docs/9.3/static/monitoring-stats.html)
tup_returned bigint Number of rows returned by queries in
this database

Imagine following query and result:

pgsql=# SELECT datname, connections, queries, tup_returned FROM
pg_stat_database WHERE datname = 'dbname';
datname | connections | queries | tup_returned
----------+-------------+---------+--------------
dbname | 0 | 1 | 39824
(1 row)

What's my problem? This (test) database isn't used by any user/script,
password was set randomly and I don't even know it. Database is left
untouched, tup_returned climbs quite high at rate ~ 65k per hour. btw.
there's only one table with 2 rows inside.
Same thing happens for all 9.3 instances in all databases configured in our
environment.

I'd be very glad if someone could explain to me what should I expect from
tup_returned or how can I meter "rows returned from database".

Best regards,
Borys Gogulski