This is merely speculation, but knowing Blizzard, I could see this as being a possible "fix" to something they see as a "problem."
In the 2.1 patch notes is states that Mining a node with a mob near by that would not normally aggro will now cause that mob to come attack you. From my experience, chest openings and node mining see to be on par with each other for getting a mobs attention. While currently when doing Arcatraz, for example, you sit there and a mob does get agro'd but after not being able to get to you after a period of time, you have a window to open the chest.
I think they may have increased to aggro pulse and it will pull more than just one mob now. So, while there is no solid evidence of this yet (because the servers are still down), we should know more tonight.
-----)(Please leave the copyright text intact)(-----
This post is copyright by the user posting it and MMOwned.com - World of Warcraft Exploits,Hacks, Bots and Guides, where it was posted. You may not copy or reproduce this information on any other site without written permission from both the poster and MMOwned.com