She could be referring to what Jenner whispered in Rick's ear. On the Season 1 Blu-ray, if you increase the center channel volume (if your TV allows), you can hear what he whispered. What he said was revealed in the season two finale.

I could be wrong, but I threw this in nonetheless.

 

That seems like something you wouldn't need to rewatch to catch though..

 

I joined the site because I'm trying to find out what I saw whilst watching this episode a couple of days ago. I've seen the ep about three or four times, but only noticed this last time.

Right after the group get into the CDC and jenners meets them in the hall, there is a close up of Lori. Behind her, a figure walks past her. All you can make out is a black hood. It's like a grim reaper! I wonder if this is what Jacqui is referring to???

maybe it was just a reference to Michonne's future emergence?

Annoyingly, when searching tinterweb, it's really hard to find out anything about what this might be

 

Maybe it's a TV crew member or something that they didn't see when editing. I know this is far fetched but it's a possibility.

 

Maybe it's just innocent, but it looks really weird. Couldn't upload a video, this photo should show you what I mean.

 

In an other thread they were talking about Sophia's death forshadowed by Carol. I don't believe that but it could be possible.