Cannot find hstore operator

Hi,

during maintenance I saw a lot of lines in my postgreslog saying:
CONTEXT: SQL function "line_function" during inlining
automatic analyze of table "osm.planet_osm_line"
ERROR: operator does not exist: public.hstore -> unknown at character 45
HINT: No operator matches the given name and argument types. You might
need to add explicit type casts.

Now the hint gives me an option but I really don't like the sprinkling of
::text in all my functions
When executed (with search_path=public) this function works correctly, and
I doublechecked that all (or at least a lot of them) hstore related
functions are present in the public schema.
Are there any other solutions to this?

Paul

PS please cc me when answering