Nothing wrong with that. If you look at the Display settings in Android Settings, you will probably find that the default is for it to turn off the screen after so many minutes and to then go into sleep mode after some number of minutes.
The idea is that if it is not being used, it is put in low battery usage state to save the battery.
What you experienced is simply the way it was supposed to function.
One other thing - you said "I have the 9.7" 16 gig model."
There dozens of companies which make tablets (I'm assuming you device is a tablet) and telling us the size and amount of storage of a tablet does not let us identify the tablet.
Next time give more information about the device you are using - brand, model, size, storage, etc. It also helps to know the version of Android being running. You can find that in the Android settings under About tablet.