Gabriel knew something was wrong the instant Zoe pushed the both of them to the ground and tucked her face into his shirt. He has stayed under the shadow for so long that he could recognize that move any day, anytime. Not to mention the desperation in her eyes for those seconds both of their eyes met. She looked like a deer caught in the headlights.
Hence he didn't ask nor move away, rather gathered her in his body and wrapped his arms around her head so they looked like lovers fooling in each other's arms. Zoe did not seem to complain, rather she leaned further into his touch and they remained that way for a while.