client.cancel_observing doesn't appear to cancel callback

[pawelevans]

Hi, I am using coapthon3 with remi (a gui based python web server) whereby the user can generate coap messages from a browser.
Setting an observe is working fine, and when the user cancels this 'client.cancel_observing' is called on receipt of the next notification and issue's a RST to the remote. If the observation is cancelled, why is my callback function still being called for new notifications, albeit no more RST are sent out, just ACK's?