mecanim animation runs at random speed on iOS

I have a character that moves to point on the screen when that point is touched. The character has a simple mecanim animation controller containing a walk animation and a spinning kick animation. the following problem happens when when running in the editor and running on the iPad. When I first run the app (click play in editor or run on iPad) the animations play at the correct speed. if i stop and start the apps the animation play at a progressively slower and slower pace each tim i run the app and bottoms out about half the normal playback speed. if i close unity and re open it or close the app on the iPad in the multitask bar this resets the animation back to the proper speed. Is this yet another mecanim bug or am I missing something. Thanks