If you're running a Tribe query, some functions are added to filters that are basic to the WP_Query class, which is making for some unexpected SQL in following custom queries which have nothing to do with events.
Tracked it down to these specific filter adds:
lib/tribe-event-query.class:31 add_filter( 'posts_join', array(__CLASS__, 'setupJoins' ), 10, 2 );
lib/tribe-event-query.class:33 add_filter( 'posts_fields', array(__CLASS__, 'setupFields' ) );
There should be a complementing method in this class, that hooks onto the end of the WP Query and removes these filters.