I have a problem I thought was because the browser, but I see this in other computers so I guess I am doing something wrong in the model config. It seems the materials get broken in the preview editor and the model ignores some maps .I looks very reflective, like it is only using an environment map for reflection.
Take a look at the model Dwarf for example, or my most recent upload Red Sonja. In this one only happens in the armor, but in the Dwarf happens in the whole model.
The model looks good when you view it, it only happens on the preview thumbnail.