Since a few versions ago (I think 3.0.6f7) my HP Bars have started having some strange bugs.
Some context to the problem :
My player has a HP Bar anchored to the top-left of the screen. I also give every Enemy in the game a HP Bar(instantiated in code), and make the Bar invisible(via SetActive(false)) in Initialize. When an enemy takes damage for the first time (and so has 100%< HP), I make his HP Bar visible (by doing SetActive(true)).
As soon as I set an Enemy's HP Bar to Active, the player's HP Bar snaps to the center of the screen, as if gaining an offset from the top left. This lasts for 1 frame, and then it snaps back to normal. This happens every single time I set an enemy's HP Bar to Active

I have looked through my code, and there is code that moves the HP Bars of enemies, but no other UI elements have code that change their positions.
The NGUI hierarchy looks like this :
UIRoot (My code here for instantiating player HUD and enemy HP Bars)
-Camera
--Anchor
---Enemy HP Bars
---Players (UIPanel)
----Player 1 (My code here to manage HP Bars and other elements)
----- HP Bar
Please let me know if you require more details