She is certainly NOT scared, in that context. She is probably angry or is resource guarding you and/or the place she was in on your lap. It is also possible you are allowing or pushing the 2nd dog, into HER SPACE. Nobody likes to be crowded and have somebody get INTO THEIR FACE and SPACE. Don’t keep dong this…. or you may end up with a dog fight – in your lap. Pet one dog at a time (preferably on the floor) or put one of EITHER side of you (on said couch) rather than in your lap. That way they are equal, but separated.