I don't think it's a coincidence. I'm convinced that he goes "on vacation" when he gets early-warning from his contacts that a serious story is about to break. And for two reasons: One reason is to get all the information without the distraction of putting on a program (that's what highly entertaining and smart subs like Mark Steyn are for). Another is to stay mum on the breaking story, let all the pundits fall all over themselves getting "what it all means" wrong, and then Rush comes back after a couple days or so to give listeners his unique angle with a sack of facts he is confident about.
Rush isnt on Vakay, James and He are doing the Up FRONT meetings - working with annual advertisers to solidify sponsorships for the next broadcast year. Hes working!