Yeah, I al;so started a 1972-sish Johnson which afdter the event we worked ut the first fuel was coming up for it;s 10th birthday..... and that was premix!
yes, it smoked like a 40 a day Marlboro* addict on the initial mix, and did run a lot better on a fresh stuff, but I guess after 10 years the premix had propably evaporated enough of the petrol to make it compatible with your avrerage seagull engine!
Back in the more normal world, I also have had no perceptible issues with a few months of storage. Due to the new crew I'll be interested to see how my current stock in the boat burns - it's now been sat for nearly 10 months.
*other brands of alegedly killer adiction are available