I haven't asked if you have GSX installed. I've asked you if you have a GSX folder in your FSX\fsdreamteam\Couatl folder, which might explain why you are seeing that message. The Addon Manager installer updates GSX if it finds its folder so, even if you haven't run the full GSX installer yourself, if the GSX folder was still there for some reason (if you ever installed GSX in the past) the Addon Manager will update its code anyway, and that will trigger an airport cache rebuild every time you add a new scenery.
Not that this is a problem in any way, the airport cache that its being mentioned it's not the FSX one (although FSX itself will also rebuild its own cache when you add a new scenery ), but it's an internal cache used by GSX only, or any other Couatl plugin that might need it.
