Did anything come of this?  I have a similar issue with a DAM asset being returned as application/save.

I have some raw HTML files in DAM that I've activated.  In the DAM asset view, it's indicating "text/html" as the asset type.  When I visit the URL of the activated asset, the http response delivers content-type application/save.text/html is defined as a mime type in the Sling Mime type service.Are ...