Honestly, Cassio hadn't known that Kyra had left. He didn't think she'd told him, and he didn't keep tabs on her in this place. He was able to find the people that owed him things, so if that wasn't taking place then what did he care? Cassio's worldview centered on one thing: Cassio.
He'd been on his bed when she knocked, but it took him a little longer than usual to answer the door. He looked at her impassively as he opened it.