Fianne ~ Scarlet does the same thing with fussing at her feeds, She pushes the bottle out and sooks and shakes her head like a fruit loop because she's still hungry - She especially does it when DF feeds her because he holds her differently, I've noticed she does it alot when she's not comfy and holding her closer to my chest helps.
DF thinks they're mini temper tantrums and she's getting ready for when she's a toddler. lol.