If the aircraft is mid 1943 or before, the standard USN/USMC paint scheme was Blue Gray over Light Gray. The decal sheet is most likely mistaken. Unless it was a field applied scheme using the new ANA-607 Sea Blue color introduced in summer 1943 for the Tri-Color scheme. Which is possible. But having just had a quick look at the decal sheet directions online, it appears to be an early war Blue Gray over Light Gray.
And you’re very welcome Randy. I would also second the recommendation for the Squadron book mentioned above.