Outside of AE, in the Finder (I’m on a Mac).
It’s not an OS thing, though. These are the same kind of icons Photoshop generates unless you turn off the option in Photoshop’s preferences. So, these icons are baked-into the files by AE as it renders.
I like the icons OS X’s Finder can generate better if I need to have icon display turned on, so I would love to be able to have AE *not* create icons for the files rendered to an image sequence.
Right now, if I get really annoyed, I use a contextual menu plug-in to nuke all the icons when the render is done. This, however, seems silly as it just feels like a preference ought to be able to be set somewhere to stop this behavior in the first place. 🙂
-Matt