Indeed, Severus was not a hugging sort of person, unless the other person in said hug happened to be Lily. So when Miss Pond stepped forward, he stiffened automatically and took half a step backward, in order to fend off any such affectionate attack.
He recovered some semblance of his good humor, however, almost instantly at what she said. He didn't think Black, Miss Granger, Potter, or Weasley would have enjoyed being levitated, even if they had been conscious at the time. Especially not Weasley, who would have been in agony because of that broken leg.
But still, the thought was a kind one, and he appreciated it, the aborted cuddle notwithstanding. "You're too kind," he told her quietly.