Or, she could have the evidence that breaks the high profile case Nick was working ever so hard on for weeks...resulting in he being extremely excited about the whole ordeal. And instead of the playful squeeze of the arm or pat on the back, all he can do is kiss her. It would be quick at first, then when both realize they both want it, a second one. You know, that split second hesitation when they break from one another, catch a glimpse of the other, then move in for the second. It wouldn't matter to me who'd initiate the kiss, but whoever would, would definitely catch the other off guard. And yes, in a good way.