Oracle 10g v$database_block_corruption

I have run RMAN with

BACKUP VALIDATE CHECK LOGICAL DATABASE;

This does not report any errors

But when I access v$database_block_corruption it reports over 180 errors

And then the query

COLUMN owner FORMAT A20

COLUMN segment_name FORMAT A30

SELECT DISTINCT owner, segment_name

FROM v$database_block_corruption dbc

  JOIN dba_extents e ON dbc.file# = e.file_id AND dbc.block# BETWEEN e.block_id and e.block_id+e.blocks-1

ORDER BY 1,2;

Retunn 3 tables ( and some indexes)

BUT

When I read the tables

select * from <tablename>

There are no errors

And an full export of the tables has no errors