iPhone, audio book does not restart where i stoped

[crazycat]

I am using my iPhone as a secondary phone, mostly to listen to music and audio books. When i hit the gym i listen to the Audio books, i will manage to listen to 30-40 mins at a time. The problem i have is that after i stopped my workout i would pause the book, when i would come back to the audio book sometimes it would not start where i left it, other times it would. I am unable to pinpoint why this would happen. I have not synced it with my laptop, i would just switch the phone off when i would sleep.

Does anyone else have a similar problem and knows how to fix it?

Thanks in advance