google-map.php “modified”?

i received a notification from Wordfence about a file modification i did not make:

Warnings:
* Modified plugin file: wp-content/plugins/advanced-custom-fields/core/fields/google-map.php

the google-map.php file itself still bears its original datestamp. when i download a fresh copy and compare them, though, i do find this slight difference:

Desktop> diff orig-google-map.php google-map.php
284,285c284
< $action = is_admin() ? ‘admin_footer’ : ‘wp_footer’;
< add_action( $action, array( $this, ‘input_admin_footer’) );
—
> add_action( ‘admin_footer’, array( $this, ‘input_admin_footer’) );

i’m running the latest non-pro version of ACF and the latest non-pro version of Wordfence.

should i be nervous about this change? it looks pretty innocuous. but i don’t understand where it came from.