So, with this system your chance of getting a quest item increases as you farm it. There is apparently a base drop rate now of 45% which, depending on how long you farm a quest item, that percentage will gradually increase. Of course as soon as I read this I did notice with the quest I was working on that it did drop more frequently/faster for the last 4 quest items I needed.
Hmmm has anyone else noticed this? Here is the link to the article....interesting stuff. Hopefully I explained it properly. Here is a link to the article.