Index contains unexpected zero page at block

[Victor Blomqvist <vb@xxxxxxxx>]

From time to time I get this and similar errors in my Postgres log file:

< 2015-12-17 07:45:05.976 CST >ERROR:  index "user_pictures_picture_dhash_idx" contains unexpected zero page at block 123780
< 2015-12-17 07:45:05.976 CST >HINT:  Please REINDEX it.
< 2015-12-17 07:45:05.976 CST >CONTEXT:  PL/pgSQL function select_pictures_by_dhash(bigint,integer,integer) line 3 at RETURN QUERY
< 2015-12-17 07:45:05.976 CST >STATEMENT:  SELECT * FROM select_pictures_by_dhash(8559245352688506666,100,0)

I have tried to recreate the index (create new index, drop the old one), but it doesnt help, the error comes back anyway. Also, its not there all the time, when I tried to rerun the statement from the logfile above a couple of hours later it worked fine without any error.

The server is a read slave, set up with streaming replication. We run PostgreSQL 9.3.5.

Is this anything I should be worried about, and if so, what can I do to fix it? Will it be fixed with a newer version of Postgres?

Thanks!

Victor