Yeah, they're pretty liberal with handing out the term "featured."
In terms of getting initially featured, it's easy to get a hub through QAP and get featured. Assuming you've got a well written, well organized hub with some media, then it should end up being featured no problem.
In the long term, all you need is a half dozen to a dozen search engine visits each month to keep a hub featured. If your hubs have searchable titles and content (i.e. they answer a question or address a topic that people are going to be searching for), then it shouldn't be hard to achieve that.
However, I noticed that most of your hubs are relatively new. Hubs are given a grace period (it used to be two months or so, but now it's going to be longer) in which to get some visits. Sometimes it takes a few weeks or even a few months before a hub floats up to a stable position in the search engine results. So it could be that all of your hubs are still within that grace period.
After a hub has been published for about two or three months, take a look at your traffic stats. If the hub is in the double digits in the "30 day" column, then you've got nothing to worry about. If it's single digits, then the hub might lose its featured status sometime in the future when that grace period is over.