Seems to have gotten worse in the last few years for sure, but the official fuel shelf life is 3 months according to BP. But then chuck that in a plastic tank in the sun with an open vent and you can halve it again.
Best thing for your outboard is to run fresh and preferably 95 octane fuel, and quality oil (read: Not Valvoline).
Glad to see you got it ripping, sorry I didn't see the post before hand.