Tom answered this question in his comment above but I don't know how to mark a comment as a solution. This is what he wrote:
"It sounds like your static content files might not have inherited the permissions you've set on the parent folder. To blanket set the permissions on all files and folders, go to the folder properties of the parent folder, click the security tab and select advanced, check the Replace all child object permission entries with inheritable permission entries from this object then click Apply."