I checked the store, their is no update in it. I am in Az. I don't know if that makes a difference or not. I currently have 8.1 preview, but I can not find the update in the windows store.
I haven't been able to try it properly, but I think this might work:
Use the Upgrade Assistant and run it, and
Upgrade Assistant: FAQ - Microsoft Windows Help
Then I think it will show you a "Go to the store" link which will take you to the correct Windows Store page.
- Windows 8.1, 10