I've noticed in multiple zones that agro has changed since the code change. Before when I would pull a single mob, anything I would pull would agro the mobs within its agro range but that's all. Now if I pull a mob, it pulls everything within it's agro range, and then the additional mobs also pull everything within their agro range.
This is normally pretty subtle, but especially on events such as the part of Fennin Ro's event where Javonn, etc spawn with their guards it's become considerably more difficult to split than it was a couple weeks ago. It's also pretty noticeable on the deathlings in VP, where pulling one ends up chain pulling every single deathling at the same time.
I think this might cause some problems with reaching the agro limit much faster than before too.