I have been exporting TGA sequences with alphas from after effects and when I open them in Photoshop I can see a strange white rim (usually) of pixels around my art. Sometimes it's just a tiny cluster of pixels too. They are not seen in the alpha though so I know they aren't really supposed to be there.
I have tried premultiply and straight alphas. I've also tested putting a black background behind the comp in AE and the garbage goes away but the alpha becomes a solid white.
This isn't really a huge problem but sometimes when the client sees white in the RGB they freak even though they know it's getting keyed out.
This is also just after effects footage from a comp. There are no external pieces of art other than photoshop comps.