It took him too long to realize her eyes were open and he wasn't just filling in the gaps of this image, effectively freezing him in place for being caught staring and thus forced into this awkward situation of having no memory of her at all. Greeting was a good enough place to start, though, that was how most people met and Tony, if only because he didn't remember the first time, was in the position of meeting this lady so familiar with his bed. He let himself stand up, at least to feel taller and more in control of this situation before he could come up with an eloquent response that summed up his personal conflict for her, "Hey." It was nuanced. An empathetic person could have read a lot into that word.