Currently, both quests and subquests both use the same scroll symbol. If there is no need to return to a quest location, I've seen that scroll go white, but if you will need to return, it stays the same tan/beige color until the quest is complete.
I'm thinking that subquest locations should have a different icon, or perhaps just a different (third) scroll color, and that 'triggered' quest locations should change color to other than tan or white, so that you know that you've been there already if you have a lot going on.
