Well I assume that is what is happening. It is grayed out without a check in that box in this Mac driver though. Oddly it allows you to select one or the other as an option of a checked box, but not both at the same time as it does with matte media. It's probably a default setting but they don't tell you. I think this was changed to this set up in later driver updates. Don't remember.
For the most part I am using QImage with these gloss media jobs and it always shows me the output resolution, which I selected as rendering resolution of 600 ppi and output resolution 2400x1200 dpi.
I am using a windows xp system and when i select a gloss type media and max detail the driver auto selects more passes,i do not know if this the case on a mac or not,i am using the Z3200, which i think is the same in that respect,it grey's out the more passes box but inserts a check mark in the box,hope this sheds some light in your question. Milt