Ok so here is the story. I got to know about this tweak called SMSTamper and i installed it on my wife's iPhone 4. I expected that after the tweak is enabled she will get a timestamp on each of the imessages she sends me. Since it did not work i removed the tweak. Now the problem is that all the messages i sent to her from my iPhone 4S (tweak never installed on this), i do get "Delivered" for the latest iMessage but that immediately changes to a time stamp as for example, "Read 1:20 PM". I am confused as to how this thing started giving time stamp to the latest messages instead of the Delivered message and that too in my phone which never had the tweak installed. Am i missing something ? Edit: Is it probably because the option "Allow others to be notified when you have read their message" is enabled on my wife's iPhone ?