Are you sure you don’t have a menu set in Appearance > menus?
Another possibility is cached pages.
Thank you for the reply Datasoftict. I was able to find the problem and fix it via my header.php file. To fix it, I found the wp_list_pages usage and the sort_column parameter…
<ul>
<?php wp_list_pages('sort_column=post_date&depth=1&title_li='); ?>
</ul>
I changed post_date to menu_order…
<ul>
<?php wp_list_pages('sort_column=menu_order&depth=1&title_li='); ?>
</ul>
Thanks again!