Why would get_posts be ignoring posts with 2-digit ids?

Question

I'm using this code to list child pages of the current page and similar code to get child pages of all ancestors to use in a sidebar contextual hierarchical nav menu:

$pageset = get_posts('numberposts=0&post_type=page&post_parent='.$wp_query->post->ID);

For some reason, both iterations are ignoring posts with a two-digit post id. Everything else shows up fine.

Am I missing something? Do I have a setting that's incorrect? I'm banging my head here...