Strange discrepancy in query performance...

I'm hoping that someone on the list can help me understand an apparent
discrepancy in the performance information that I'm collecting on a
particularly troublesome query.

The configuration: pg-8.2.4 on RHEL4. log_min_duration_statement = 1m.

In my syslog output, I see entries indicating that the
JDBC-driver-originated query on a table named 'city_summary' are taking
upwards of 300 seconds:

Oct  1 18:27:47 srv3 postgres-8.2[1625]: [12-1]
LOG:  duration: 307077.037 ms  execute S_42: select * from city_summary
      where  state = $1 and city_master_id = $2 and res_type =
'single_family' and date = $3
      and range = 90 and zip = $4 and quartile  = '__ALL'
DETAIL:  parameters: $1 = 'CA', $2 = '291', $3 = '2007-09-28', $4 = '__ALL'

However, if I run the same query on the same host at the same time that
the Java application is running, but from the psql  command line, it
takes only 0.37 seconds:

 > time /opt/postgres-8.2.4/bin/psql --port 54824  -U postgres -d
altos_research  -c 'select fact_id from city_summary where state =
\'CA\' and city_master_id = 291 and zip = \'__ALL\' and quartile =
\'__ALL\' and res_type = \'single_family\' and range = \'90\' and date =
\'2007-09-28\';'

 fact_id
----------
 46624925
(1 row)

0.00user 0.00system 0:00.37elapsed 0%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+285minor)pagefaults 0swaps

The output of 'explain' seems to indicate that the right index is being
used:

QUERY PLAN
 Index Scan using city_summary_pkey on city_summary  (cost=0.00..12.27
rows=1 width=2721)
   Index Cond: ((date = '2007-09-28'::text) AND
                (state = 'CA'::text) AND
                (city_master_id = 334::bigint) AND
                (quartile = '__ALL'::text) AND
                (range = '90'::text))
   Filter: ((zip = '__ALL'::text) AND ((res_type)::text =
'single_family'::text))
(3 rows)

The index looks like this:

# \d city_summary_pkey
Index "public.city_summary_pkey"
       Column       |  Type
--------------------+---------
 date               | text
 state              | text
 city_master_id     | bigint
 zip_master_id      | integer
 res_type_master_id | bigint
 quartile           | text
 range              | text
primary key, btree, for table "public.city_summary"

Any ideas on why I am seeing such a big difference between the two
measurements (JDBC/syslog vs. command line)?

Thanks,
Jason