Why pgAdmin III guru suggests VACUUM in 8.1

I'm using Postgres 8.1 in Windows XP

Sometimes when using pgAdmin the following Guru hint appears suddenly:

"Running VACUUM recommended
The estimated rowcount on the table "firma1.algsa" deviates significantly
from the actual rowcount. You should run VACUUM ANALYZE on this table.
Instead of issuing a manual VACUUM ANALYZE command on this table (you can
use the pgAdmin III maintenance menu for this), running VACUUM ANALYZE on a
regular or automated basis should be considered. This can be achieved using
a scheduler. PostgreSQL also supplies the pg_autovacuum daemon, which will
track changes made to the database and issue vacuum commands as required
automatically. In most cases, pg_autovacuum will be the best choice. "

I have noticed in Postgres log, that autovacuum processes my cluster
regulary.
So in my knowledge, this hint is wrong.
Please confirm that guru is stupid.

Also I followed this hint and got the results:

INFO: vacuuming "firma1.algsa"
INFO: index "algsa_pkey" now contains 122 row versions in 2 pages
DETAIL: 0 index pages have been deleted, 0 are currently reusable.
CPU 0.00s/0.00u sec elapsed 0.06 sec.
INFO: "algsa": found 0 removable, 122 nonremovable row versions in 4 pages
DETAIL: 0 dead row versions cannot be removed yet.
There were 0 unused item pointers.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.06 sec.
INFO: analyzing "firma1.algsa"
INFO: "algsa": scanned 4 of 4 pages, containing 122 live rows and 0 dead
rows; 122 rows in sample, 122 estimated total rows

So it seems that vacuum did make anything.

Andrus.