I took Ghost's unease at being able to sense Jon was in danger right before he was attacked. Sensing the Others' arrival makes sense too, but we won't know for certain until the beginning of the next book. IIRC, GRRM will be opening with "two major battles". Most likely Stannis' siege on Winterfell and, as you said, the Others at the Wall. Are there any other things going on elsewhere? Ironborn attacks? Dornish displeasure towards Kings Landing? City-state battles in Slavers Bay?