Music just stops

[jtfullofit]

I wanted to use playlists during my yoga class.  However, the two times I have tried, it just shuts off about 20-30 minutes into the class.  Not exactly sure why.  I am downloading the playlists and connecting to a stero with bluetooth using my iphone.  I do not have the same problem with my playlists on ITunes.  Not sure what to do?

There is another instructor at our studio who has had the same experience.