FATAL: could not read statistics message

I am using postgresql 8.1.0 on an Xserver running MacOS 10.3.9.  I am
getting the following in the log every minute for the past couple of days.
The database is otherwise running normally, as far as I can tell:

2006-05-16 07:26:01 EDT   FATAL:  could not read statistics message:
Resource temporarily unavailable
2006-05-16 07:27:01 EDT   FATAL:  could not read statistics message:
Resource temporarily unavailable
2006-05-16 07:28:03 EDT   FATAL:  could not read statistics message:
Resource temporarily unavailable

I saw a previous message in the archives, but it did not appear that any
conclusion was reached.  Tom suggested that an EAGAIN signal was being
received from the system, but I'm not sure what this means exactly or why it
is happening now, as we have had the server running for months.

Any insight?

Thanks,
Sean