He ignored her jibe, just as he ignored her question. Bruce knew she was teasing him, just as well as she knew that he had, in fact, missed her. She wanted to hear him say it though, and the fact that he couldn't, wouldn't admit it - not in this guise - would likely be a familiar, if unsurprising, frustration.
Studying her, Bruce was pleased to find her in good health. Better than when she'd left, even. Her skin had a warm, sun-kissed glow, and she seemed to be more at peace with herself than he remembered. He knew why she had left so suddenly, and he knew where she had gone. Tracking her escape from Gotham as unobtrusively as one can while essentially stalking them, Bruce had kept an eye on Selina to make sure she was alright and that the demons that had chased her from her home - his demons - weren't causing her greater trouble than they were worth.
Her reappearance here was unexpected, but the faintest of smiles suddenly ghosted across his lips, possibly providing her with more of an answer to her question than any words he could have spoken would have, as a warm rush of pleasure ran through him, quickly suppressed at the realization that she'd come back.
After a long, assessing silence, Batman finally said, quietly, "I hear Saudi Arabi is lovely this time of year."