Not sure what's going on exactly, but it seems on two different IPS sites I run some images retrieved from S3 via CF ala a CDN CNAME (i.e. cdn.site.com) return a 403, however the majority return just fine.
File types that return 403: ICO, SVN
One site returns SVN fine, both sites 403 for ICO
Both sites return JPG, PNG, GIF fine.
I've compared htaccess, S3, CF configs from both sites and haven't spotted anything different between them.
Anyone have any ideas?