Default [Q] Speaker on when using headset in phonecall

Hi,

After updating to Kitkat (4.4.2) on my One I have a strange, though not persistant problem. When I use the HTC headset for a phonecall, the speakers in the phone are turned on when I make the call. When I turn the speakers off, sound goes as expected through the headset.

Does anyone have similar problems - and maybe even a fix/workaround?

Best regards,
Lars