you should have said, yes what is it, as soon as she said your name, and if you know it's a rumor, then you heard what it is right? so, at lunch explain to her in as nice as way as you can, that it takes a woman to speak to a woman, and a coward to talk behind her back, now ask her what her problem is with you and what caused her to say, so that they two of you can work on fixing that problem in a good way, or for her to forever hold her peace about it..k?!