Red box on Finder icon in Dock
I ended up reporting it as deeeeeeekun suggested. Some of the suggested workaround in the comments were also suggested to me. This is the solution they gave that worked:

1) cd getconf DARWIN_USER_CACHE_DIR

2) attach com.apple.dock.iconcache to radar

3) rm com.apple.dock.iconcache; killall Dock

I'll update the answer when they give me the reason why the redbox happened.