If Ginny had reached out to take Hermione's hand she wouldn't have protested. When leading someone to a location it was perfectly natural to use a small amount of physical contact to guide them regardless of gender. Not to mention that such actions were deemed typical in most situations.
After a few twist and turns the two girls were making their way up the stairs of the Astronomy tower and Herimione found that the thought of being completely alone with Ginny was causing butterflies to flutter around her stomach. "Not that it would take much," she joked in response as she hugged herself and rubbed her arms. The dress she wore was not conducive to the chill in the tower and goosebumps grew on her flesh.
"A little," she nodded as she continued to rub her arms for warmth. "I just should have worn something a little warmer." Hermione had worn a jacket that evening but her annoyance with Cormac and her need to escape had caused her to forget to grab it on the way out.