Just came across this today. I wonder if this is the reason Musk is rattled by anything Bezos does and says in aerospace:
http://www.geekwire.com/2015/blue-origins-rocket-landing-patent-canceled-in-victory-for-spacex/
http://www.geekwire.com/2015/blue-origins-rocket-landing-patent-canceled-in-victory-for-spacex/