It probably isn't a dream. She's probably visiting for reasons known only to her.

You could try this if she appears again -- ask her aloud what she wants. Ask her why she is making her presence known to you. Reassure her that you both are fine and there is no reason for her to check up on you. Mentally surround her image with white light, tell her you love her and say goodbye. Then turn over and go back to sleep (or at least give it your best shot).