Due date issues

I also am following my pregnancy on the "what to expect" app and a couple of other apps. I have found that my due date is entered in correctly this app had my pregnancy progress off by one day. For example... My other apps say that I am 26.1 where as this app says that I am 26.2  Any one else having this issue? I've emailed the support people, but just wondering if I was the only one with this problem. Thanks!!