Clementine had taken down the main threat and she went in to check on Glenn, this was when Jason used the opportunity to retrieve the fragment that existed within the carcass of this body.
Unknown to Jason, Clementine was watching him from the entrance of the tent, she noticed how he didn't want to leave the zombie's side and was instead, hovering.
He was stalling and this was why Clementine left him, it was to see why he was.
"What's that?" Clementine thought to herself, she saw Jason retrieving some sort of stone from the zombie's corpse.
She wanted to barge out and ask him what it was but Clementine knew she would get more information observing as opposed to confronting him directly.
This was a smart move and Clementine hated to admit it but she couldn't trust Jason anymore.
"W-What?" Clementine thought to herself upon seeing what Jason was doing with the fragment.