Where is my "play" symbol?

I have updated to iOS7 on an iPhone 4. (I have also updated to 7.0.2 and the problem is not resolved.) When I play music in iTunes or listen to an audiobook with Audible I no longer get a "play" symbol up by the batery charge indicator. I get all the other symbols up there (bluetooth, do not distrurb, compass for GPS) but the play symbol (sideways triangle) does not appear. IT did when I first upgraded but something has happened and it no longer shows up. I have restarted 5 times. I have upgraded to 7.0.2. Can i anyone point me in the direction to get this fixed? It seems trivial but I actually use the symbol to know if my audiobook is still playing in the car when I take a call. It is a useful visual refernce for me. Please help.