Log says temporary files are being created

PostgreSQL 5.3.2

I am seeing entries like this appearing in my PostgreSQL log. 

Log entry:

temporary file: path "base/pgsql_tmp/pgsql_tmp10336.0", size 17809408

1)      Should this concern me?

2)      What would I need to modify in my configuration in order to stop temporary file creation from occurring?

Thanks,

Lance