Welcome to Android Central! What app were you using? Restarts like that can be associated with an app crash, which wouldn't be a problem with the phone per se.
Welcome to Android Central! What app were you using? Restarts like that can be associated with an app crash, which wouldn't be a problem with the phone per se.
Try clearing Word's app cache and data in the App Manager. Then see if it happens again in the next few days. If it happens again, but not while running Word, then bring the phone back to the store and see if they can give you a replacement.