No it does not mean that they haven't opened your wife's file. They probably felt that in your case they need some extra information and for your wife they didn't thinks so for the time being. Usually all files for a family are opened at the same time (this is as per some friends, not a legal opinion).
No matter, when you file your response they'll look into all of the documents again. Pray to God that they retain the same opinion and issue you the approval.
I'm also on the same boat, I recieved my RFE on July 3rd and submitted reply on July 23rd. In my case message is changed but in my wife's case it is not (since there was no RFE for her).
