Query_post() – unsafe?

I would ask this on the Page Builder support site, but it is quite inactive and questions seem to be going unanswered. I think it’s a simple coding question so perhaps here will be fine.

I’m using the ‘grid-loop’ to display posts on pages. However, I’m creating multiple ‘grid-loop’ files for each category, since a different category of posts will be displayed on their own respective page.

For each new grid-loop file, I’m adding in query_posts( ‘cat=ID’ ); and using that to display the category I want. I’ve read that using these queries is unsafe or something? I’m using a different file for each category’s respective loop.

Here’s the code for category 5’s loop.

<?php
/**
 * Loop Name: Grid Child
 */
?>
<?php if( have_posts() ) : $i = 0; ?>

	<div class="vantage-grid-loop">
		<?php
		query_posts( 'cat=5' );
		while( have_posts() ): the_post(); $i++ ?>
			<article <?php post_class(array('grid-post')) ?>>

				<?php if( has_post_thumbnail() ) : ?>
					<a class="grid-thumbnail" href="<?php the_permalink() ?>">
						<?php the_post_thumbnail('vantage-grid-loop') ?>
					</a>
				<?php endif; ?>

				<h3><a href="<?php the_permalink() ?>"><?php the_title() ?></a></h3>
				<div class="excerpt"><?php the_excerpt() ?></div>
			</article>
			<?php if($i % 4 == 0) : ?><div class="clear"></div><?php endif; ?>
		<?php endwhile; ?>
	</div>

	<?php vantage_content_nav( 'nav-below' ); ?>

<?php endif; ?>

The query is near the top. Will I have any problems with it? It seems to be doing exactly what I want, and I suck at anything coding related so it’s the best I can do.