It wasn't a proud habit of his. Gus knew how disgusting and bad it was, but he didn't particularly care to have it pointed out to him. He rolled his eyes then turned around, having recognized the voice. Gus wasn't exactly in the mood to take any hassle lightly, but he'd at least try not to take his frustration out on Gianna.
"I've got lots of them," he said, not letting her distaste for his particular choice of stress relief deter him from finishing his cigarette. "Disgusting habits. You've seen where I live."
It dawned on him that he was nearby her place, and that the chances of running into her were pretty high -- something he should have considered sooner. Gus wasn't sure whether he was happy to see her or not; that would probably depend on how much grief she gave him.