Somewhat odd messages being logged on replicated server

I am playing with the replication on 9.0 and running into the following.

I have a primary that is running at a colo, and is replicated down to a
secondary here using SLONY. This is working normally.

I decided to set up a replication of the SLONY secondary onto my
"sandbox" machine to see what I think of it as a solution to potentially
replace SLONY. All appears to be working fine, EXCEPT that I'm getting
the following in the log.

Sep 29 19:58:54 dbms2 postgres[8564]: [2-2] STATEMENT: update post set
views = (select views from post where number='116763' and toppost='1') +
1 where number='116763' and toppost='1'
Sep 29 20:01:11 dbms2 postgres[8581]: [2-1] ERROR: cannot execute
UPDATE in a read-only transaction
Sep 29 20:01:11 dbms2 postgres[8581]: [2-2] STATEMENT: update post set
views = (select views from post where number='2040327' and toppost='1')
+ 1 where number='2040327' and toppost='1'
Sep 29 20:02:02 dbms2 postgres[8582]: [2-1] ERROR: cannot execute
UPDATE in a read-only transaction
Sep 29 20:02:02 dbms2 postgres[8582]: [2-2] STATEMENT: update post set
views = (select views from post where number='140406' and toppost='1') +
1 where number='140406' and toppost='1'
Sep 29 20:04:58 dbms2 postgres[8586]: [2-1] ERROR: cannot execute
UPDATE in a read-only transaction

When I go look at the value of "views" on both the master and replicated
slave, they have the same value..... so I'm not sure why the error is
showing up.

There are no clients attempting to connect to the replicated server at
all at this point (I will enable that later once I'm satisfied that it
is working in the general sense), so this has to be coming from the
replication system itself.

I presume that since the values are identical on both machines this can
be safely ignored, but I'm curious why it's happening....

-- Karl