Update Form_validation language lines within upgrading from 2.2.2 to 3.0.4

I am upgrading from 2.2.2 to 3.0.4 version and I have found (in Upgrading from 2.2.x to 3.0.x manual at Step 18: Update your Form_validation language lines) that Language Library line keys now must be prefixed with form_validation_.

I have ALL my keys in ALL actual text_lang.php files already prefixed with '.' dot sign.
Example: $lang['.label_iban'] = 'IBAN';

Is it necessary to change prefix '.' to 'form_validation_' prefix for the language library keys which I am using in form_validation.php file ONLY? Or not.
It is not so easy for me to do it, because I use these '.' prefixed keys also everywhere where is structure $this->lang->line('xxxxxx') (at views, controllers, helpers).

Thanks

Only form_validation_lang.php is affected ... I don't know why you would think otherwise.

I did not understand exactly it concerns only form_validation_lang.php.
I thought text_lang.php is affected too.
Thanks.