Possible stability issue: permanent hang on dropdb

Just had a very odd thing happen with an 8.4.2 database, and am
concerned it's an undiagnosed bug:

(1) created and dropped the same database 10-15 times in the course of
running some tests.

(2) at one point, dropdb hung. Indefinitely.

(3) attempts to pg_cancel_backend on the DROP DATABASE process were
futile. yet no other queries were accessing that database according to
pg_stat_activity.

(4) pg_ctl -m fast did not shut down the server.

(5) pg_ctl -m immediate did shut it down.
(5a) realized pgbouncer was still running. shut it down as well.

(6) on restart, the server took several minutes to *start* recover mode.
then it got to a certain log segment, and hung indefinitely.

(7) killed postgres

(8) restarted again. this time the server came up in about 20s, and is
behaving normally. The deleted database is not there.

Setup:
RHEL 5
PostgreSQL 8.4.2, installed from yum.postgresql.org
8 databases and about 10G of data on the server
pgbouncer running but NOT connected to the dropped database, just to two
others

I've made a full copy of my PGDATA directory if anyone wants me to test
anything.