Hangouts set as default SMS app but open in old app

[garywright1000]

I've been using Kitkit which arrived OTA on my Nexus 4 nearly a week ago but since I started using Hangouts as the default SMS app, which is fine and I've double checked and if I go to settings, wireless and networks, Default SMS app is set as hangouts. Yet when I receive an SMS and the phone is in standby, the screen lights up and shows new SMS and the option to view, when I touch this, I have to unlock my phone and it takes me straight to the old messaging app instead of hangouts. Just wondered if anyone is having the same?