Wonder if it means she didn't die, or perhaps she could be a hallucination or flashback. Wouldn't be the first time-Lori, Shane, Herschel, Sasha, Henry and several others have had post-death cameos in the main show.

FTWD itself had the weird Christmas dinner dream where Travis came back.

And Merle appeared in a hallucination before he appeared in the flesh when Daryl was looking for Sophia.