I get that too, in fact I created a post on it a few months back. It seems that if your local date stamp is DD/MM/YYYY, it will be read by Thwack as MM/DD/YYYY. So in your case the 10/09/2015 is read as 9th of October 2015 instead of 10th of September 2015. And if the date is 13th or above, then you won't see your last logged in details until such time that your local date is between 1-12.
Thanks Superfly..