pgstat wait timeout

I have a system (9.0.4 on Ubuntu Server 10.04 LTS x86_64) that is 
currently in test/dev mode. I'm currently seeing the following messages 
occurring every few seconds:

...
Dec 27 17:43:22 foo postgres[23693]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:43:27 foo postgres[27324]: [71400-1] : WARNING:  pgstat wait 
timeout
Dec 27 17:43:33 foo postgres[23695]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:43:54 foo postgres[27324]: [71401-1] : WARNING:  pgstat wait 
timeout
Dec 27 17:43:59 foo postgres[23697]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:44:04 foo postgres[27324]: [71402-1] : WARNING:  pgstat wait 
timeout
Dec 27 17:44:09 foo postgres[23715]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:44:17 foo postgres[27324]: [71403-1] : WARNING:  pgstat wait 
timeout
Dec 27 17:44:22 foo postgres[23716]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:44:27 foo postgres[27324]: [71404-1] : WARNING:  pgstat wait 
timeout
Dec 27 17:44:33 foo postgres[23718]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:44:54 foo postgres[27324]: [71405-1] : WARNING:  pgstat wait 
timeout
Dec 27 17:44:59 foo postgres[23824]: [6-1] : WARNING:  pgstat wait timeout
Dec 27 17:45:04 foo postgres[27324]: [71406-1] : WARNING:  pgstat wait 
timeout

I can't correlate events exactly, but the messages seem to have started 
shortly after I dropped a pgbench user and database. My Googling turned 
up various requests for debugging info on "hackers". Since the system 
isn't live, I haven't touched it in case anyone wants me to collect 
debugging info.

Otherwise, I plan on just blowing the install away and replacing it with 9.1

Cheers,
Steve