This call in lib/class-wp-json-posts.php (and probably elsewhere) does not seem to always work with php versions < 5.4 (despite the php docs). Yes people can probably use latest versions with their shared hosting if they know how or know how/where to look, but for those who do not will probably get pretty frustrated. Hostgator's default is 5.3. You can use 5.4 by adding:
AddType application/x-httpd-php54 .php
to your .htaccess file in the root of your file structure.
It would be good if you either chose another method to use for this or checked if the mehod is available and if not, then use a different one for compatability issues that may occur.