I just updated from NGUI 3.6.0 to 3.6.4b.
Now I have several places where anchors need a frame before they refresh.
In the .gif below, the funny spiral-like icon is anchored to the label that says "1280" and set to OnUpdate.
That label is updated in the first frame, so it changes it size.
I'm guessing the anchor gets updated before the size is changed, and that's why it doesn't anchor to the right position until the next frame.
It works if I manually call UpdateAnchors, but that seems a bit like a hotfix.

Did anything change from 3.6.0 to 3.6.4 that could cause this?