PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"

We just had a slew of the following messages in our log. How concerned
should I be at this point? I have no idea what triggered it.

Version:
PostgreSQL 9.0.2 on x86_64-unknown-linux-gnu, compiled by GCC gcc
(GCC) 4.1.2 20080704 (Red Hat 4.1.2-48), 64-bit

2011-01-31 14:16:13 PST [32767]: [1-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 22
2011-01-31 14:16:13 PST [32767]: [2-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 656
2011-01-31 14:16:13 PST [32767]: [3-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 678
2011-01-31 14:41:44 PST [4208]: [1-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 99
2011-01-31 14:41:44 PST [4208]: [2-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 223
2011-01-31 14:41:44 PST [4208]: [3-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 224
2011-01-31 14:41:44 PST [4208]: [4-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 247
2011-01-31 14:41:44 PST [4208]: [5-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 248
2011-01-31 14:41:44 PST [4208]: [6-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 250
2011-01-31 14:41:44 PST [4208]: [7-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 251
2011-01-31 14:41:44 PST [4208]: [8-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 252
2011-01-31 14:41:44 PST [4208]: [9-1] (user=) (rhost=) WARNING:
PD_ALL_VISIBLE flag was incorrectly set in relation "pg_statistic"
page 253