AIR24 change to how sounds work in iOS?

Hi there

I rebuilt an existing iOS app with AIR24 and sounds seems to behave differently. Previously if I had a looping soundtrack, the sound would stop when I put my device to sleep (and resume when I woke the device).

Since building with AIR24 the sounds continue whilst the device is in sleep mode. In my case I don't want this to happen.

Has something changed in AIR24?

Is it intentional?

Am I missing some magic setting that I should know about?

Many thanks.