I think Killing Time's comment fits well, too:
She turned away and did a double take at the sight of the filled porcelain.
A "double take" involves a bit of a delayed reaction, which I envision as having a physical component. Imagine the situation Merriam-Webster gives as an example:
His parents did a double take when he came home with a tattoo.
I imagine that they say "hi" as always and are already turning back to whatever they were doing before he entered, only to turn their heads back, startled, because by then the realization had surfaced that he has this new image on his skin that wasn't there before.
The movement may well involve moving the head backwards as when you try to assess something skeptically, frowning, symbolically increasing the distance to the subject of scrutiny, thinking "wait a minute". You can surely do a double take that way and still look away, if you want to avoid eye contact or don't want to stare; in that case you would freeze for a second, perhaps mentally "replaying" what you saw and considering a proper reaction, without taking a closer look right away.