Your local Netflix probably has a lot of content on it but there's always more waiting just over the horizon, especially on the American version of the service which has been around for much longer. This has led to many users using VPNs to change their geographc region in search of a few extra episodes of their favourite shows.
The company has been talking about clamping down on this practise in recent months under pressure from studios as the content is only licensed for certain regions. And it seems they put in some extra work on the issue over the weekend with many waking up to find that their VPNs no longer work.
It's a complicated issue in many ways, with Netflix previously being pretty blase about it - after all they're still getting paid regardless. The networks and studios have muscled in on their lost revenue and things are about to change. It's likely that there will always be some way to get around these blocks but it could become harder for regular users in the weeks and months ahead. In the meantime, if your method is still working it might be best to nab those much wanted shows as soon as possible.