For Events in the loop, include category in post_class()

Okay, this is complicated to explain, but I'll do my best...

I'm using the following code to include Events from Events+ in my homepage loop.

add_filter( 'pre_get_posts', 'my_get_posts' );
function my_get_posts( $query ) {
	if ( is_home() && $query->is_main_query() )
		$query->set( 'post_type', array( 'post', 'incsub_event' ) );
	return $query;
}

It works fine.

Within the loop, each post item is wrapped in this div:
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

This is a nice little way to really isolate different content types, post types and categories. I plan to use this to style the individual posts according to category. The problem is, with the regular WP posts, the categories get added to the class with no problem, but the Events post type doesn't include the event category.

This is the output I get for the class for the Events post type:

<div id="post-80" class="post-80 incsub_event type-incsub_event status-publish has-post-thumbnail hentry">

Compared to the output for the regular posts type:
<div id="post-60" class="post-60 post type-post status-publish format-gallery has-post-thumbnail hentry category-uncategorized">

The events don't include the event category. I would like to be able to style based on the event category like I am able to for the regular post categories.

You can examine the source code here: http://dev.prometheusfire.me/newsline-development/

Is there any modification or filter that can be added to output the event categories into post_class()? Ideally, it should output something unique like events-category-meetings, or incsub_events-category-meetings.