Sam felt mildly stupid for taking his gun now, but now there was nothing he could do about it. So he kept his mouth shut.
He didn't know how to feel, this time. The first time he saw his mother, he was being pinned to the wall by an evil spirit and she didn't touch him at all. He followed Dean, because that was something he always did, and Dean would know their mother anywhere. Sam was afraid what he remembered might be a little bit fuzzy.
Then he saw her. Nothing fuzzy about that. Mom looked like she was a little cold, and she had that look on her face that Dean often had right before he beat the snot out of Sam for being utterly obnoxious.