At certain distances - or viewing angles - I see a relatively wide bleed over. This is more than just the rim but is a gradual darkening that extends out from the wing tips.
I see the same problem with other types of edits. Fine detailed branches and bare trees are problematic. It starts with the settings that are applied during the initial rendering of the RAW file. Normally some contrast is applied and in some cases it shows up with a wide shadow. I have seen images severely criticized in PPA competitions because of this problem.
It is not unique to LR or CS6. I see the same problem with Capture NX2. One technique is to use negative selection to make sure the contrast is not applied to the blue background of the sky.