Bug in vacuum on 7.2.4?

Is there a known bug/race condition in vacuum on 7.2.4?

I find this error in my log files about once a week, but
it is not reproducable manually.  

NOTICE:  Index pg_statistic_relid_att_index: Pages 5; Tuples 410:
Deleted 449.CPU 0.00s/0.00u sec elapsed 0.00 sec.
ERROR:  MemoryContextAlloc: invalid request size 0


NOTICE:  Index pg_statistic_relid_att_index: Pages 5; Tuples 551:
Deleted 71.       CPU 0.00s/0.01u sec elapsed 0.00 sec.
ERROR:  MemoryContextAlloc: invalid request size 0



Running the vacuum again after the error occurs appears to work fine:

NOTICE:  Index pg_statistic_relid_att_index: Pages 5; Tuples 403:
Deleted 167.       CPU 0.00s/0.01u sec elapsed 0.00 sec.


The vacuum command is run (nightly) as follows:/opt/pgsql/bin/vacuumdb -a -v -z -f -e


Thanks,

- Ryan


P.S.

I just removed the -z and -e options, will run with that and see if I
can reproduce it again. (I'll run the analyze with the non-full
vacuums).

-- 
Ryan Bradetich <rbradetich@uswest.net>