Granted...his type usually had a pulse and was not room temperature. He was always willing to make exceptions. He usually didn't, Dean was a creature of habit. Dean was just as surprised as she was: maybe it was the mood she caught him, or the touching, it was quite possibly the touching. Or the fact that he felt like it was sort of building along with their friendship. Something that made this even stranger...being a friend.
The fact she didn't kiss back for what seemed like a good chunk of time somehow made him think he was actually not supposed to listen to the physical cues that were going down, but the fact that she did only moments later -- sort of saved this entire experience. He didn't really see a problem with this, he was already immune to curses, the Mark needed him alive so he didn't even fear zombieism. He reached his hand up before pulling apart and taking in a deep breath.
"...so...that happened. I'm sorry," he took in a deep breath, his face still inches away from Liv's. For a moment even wondering why the fuck he apologized. Maybe it was because Liv had blocked his exit that he didn't know how to function without an exit plan. Or he didn't know how to process EMOTION, which was a big thing for Dean. The last person he felt something genuine for...well, it was Lisa. And she now did not have any recollection of the time she spent with him or Dean Winchester at all.