It's not an issue. As Skunkboat alluded to, a counter rotating lower unit (usually the port motor on a twin) is more likely to spin in neutral since it has a tad more gear drag than a normal rotating unit due to the extra gears.
That might be the second time today, I got my data reversed. There is more drag on the counter rotating so it is LESS likely to spin. Oy, cabin fever is fogging my brain.
My starboard also spins especially when out of the water on muffs