[Pgpool-general] SELECTs sometimes being redirected (incorrectly) to master

[Henry]

Hello all,

Pgpool: 3.4.1
Pg: 8.2.6
OS: CentOS 5

I've configured multiple slaves to use pgpool in conjunction with slony.
Updates/deletes/inserts get redirected (via pgpool) to the master, and
selects are performed locally on the slaves.

Relevant entries in pgpool.conf:
replication_mode = false
replication_strict = true
weight_master = 0
weight_secondary = 1

Now, for the most part, things work fine.  99.99% of selects are executed
locally, mods go to the master as expected.

Problem is, occasionally (actually, many times a day) on our (very) busy
cluster, SELECTs from the slaves will appear on the master (despite
"weight_master = 0").

Is there any way I can *force* SELECTs to *always* be performed locally? 
In our case, these occasional selects being incorrectly directed to the
master are a problem (performance-wise).

Any suggestions are appreciated.

Thanks
Henry