Sam gave a brief nod and turned towards the door, and Dean and Amy followed suit. His father’s training kicked in as Dean’s automatic thought became tactics on how to tackle the demon when it came through the door. He looked at Amy. “Go to the window at the back of the room – that way, if Sam and I get distracted and it thinks we’re the only ones here, you can surprise the son of a bitch!” he called over to her. Amy looked suddenly doubtful at the prospect of not huddling in a group any more, and from being a noticeable distance from them. Sam caught her look and tried to reassure...
The crew of Supernatural loves to echo past events using imagery and dialogue, sometimes obvious, sometimes subtle. They're mile markers along the journey that encourage the audience to look back and see how far the show has come. Here's a few that I've noticed;
Pilot: The obvious mirror image of Mary and Jess both pinned to the ceiling.
Pilot: John hands baby Sammy to Dean and says "Take your brother outside as fast as you can. Don't look back."
Home: Sam says to Sari "Take your brother outside as fast as you can and don't look back." [both events happened in the same house]