If memory serves:
- Ripley Flares flamethrower
- Queen orders Xenomorphs back
- Egg opens
It was when the egg opened that Ripley nodded her head as if to say "oh hell no!", and then the shooting began. It seems to me that the queen had no intention of letting Ripley and Newt go, but had every intention to cocoon both. That plan back fired (pardon the pun).