Slightest misstep indeed. Like lighting up a cigarette in front of the man you're going to kill when he's holding a [i]very[/i] alcoholic beverage. He knew why she was here. Someone like her wouldn't be here for any other reason, and as soon as the flame jumped off the match (or lighter, whichever one she was using), he almost casually tossed the contents of his glass at her face, right over the open flame. With such a high alcohol content, the fumes would be more than enough to ignite the drink as it passed over the flame and into her face, and the motion held no pre-existent tells. No contortions of the face, no tensing of the muscles just prior to imminent combat, just a man emptying his drink. 

He almost felt bad for interrupting her like that, but this was life or death. You either took every advantage your opponent gave you, or you died quickly and painfully. He had no intention of doing the latter. None at all.