If he thought he was being clever, Gin could read his hand. They were too similar. Both portrayed different people on the outside and, at the same time, they hid some inner agenda on the inside. For Kisuke, he came across as a man who was an innocent shop keeper who sold products of all types. For Gin, he was a betrayer and a murderer on the outside, but on the inside, he was a man who was desperate for revenge because a man had made the only woman whom he'd ever loved cry.
And for Kisuke to use the very phrase that Rangiku used with him was enough for Gin to give the man a glare. He would never let Kisuke see his eyes fully, not like he did with Rangiku. He didn't trust the man. "It's been interesting, Kisuke," he returned casually, watching the man through slitted eyes as he saw him carry the box out into the main room. "And yourself?" He would go through this small talk if he needed to.
Just what did Kisuke want? He was sure that the man knew what Aizen had, and the fact that he came dressed as he was should speak volumes. And Rangiku hadn't murdered him--quite the opposite. She was every bit as passionate as he'd been hoping. But he was going to do everything he could now to keep her safe and protected, no matter what; if that meant confronting Kisuke Urahara, then so be it.