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(at)uswest(dot)net>