I have seen this type of extractor damage before.
Here is a copy and paste from an article I read once about the exact same thing you are seeing. He was shooting a P3AT:
"You will notice the nick in the rim fits the extractor... the rolled edge of the casing would line up with the lower part of the chamber, and the slight flat spot on the side, about 1/3 the overall distance from the rim, would fit with the barrel hood. These guns are made to extremely tight specs to operate properly, and made about as small and lightweight as a .380 round will allow. The dings are evidence of the extreme engineering that went into these pistols.
If you don't reload, you have nothing to worry about with new brass. A nick in the rim of the case will have no effects on performance. The .380 headspaces on the mouth, so no worries there. One major thing to worry about as a reloader is incipient head separation caused by weak brass. this is when the case web fails and separates, [color:#FF0000]and could cause kb[/color]."
Hope that helps