Had Balthazar been able to read minds, he would have been greatly offended by her choice of descriptions. Since he couldn't, and since he was also unaware of Lizzie's ire, he had been on his way toward the door when he felt it. It didn't feel entirely malicious, but you didn't just get flicked in the neck by some unseen force and injure it - at least not when you had been stabbed in the back by your now-boyfriend.
The angel turned and his eyes wept over people until he came to the girl with a face that told him that she knew him in some way - it was a familiar human expression for him, really. He looked vaguely amused, but the idea of walking back seemed silly so he just disappeared and re-appeared sitting at her table. Castiel's sugary drink was seemingly gone, but Balthazar's coffee was there. He didn't seem intent on speaking right away as he produced some whiskey and poured it into the coffee before taking a sip and looking at her.