He'd been prepared for a variety of reactions, ranging from the over amorous (which was unlikely given how controlled the other man seemed to be, although it wasn't entirely out of the question) to the out right explosion of anger in the form of a physical altercation (again, unlikely due to the extreme nature of the act but still plausible) but the look of shock took him by surprise. The small token of affection couldn't have been unexpected considering the past that they shared - or, the past Albus assumed they had shared and yet, the look on Severus' face seemed to say that it was the very last thing that would have ever crossed his mind.
"Er, sorry," he said, suddenly uncertain of what he had thought was painfully obvious. "I had thought you understood why I was here. In all the times we have spoken I sensed that there was more too your dislike other than a casual indifference or even a quarrel among colleagues. I want you to know that any emotional duress that I have caused you was never my intention. I can't pretend to know how my mind will work as actions are built over time and experiences have a way of coloring our motivations but from where I stand now, if I rejected you it wasn't because there was a waning in my affections for you."