I also encountered this issue. It seems that some behaviour changed. You can notice that the milliseconds are gone in the timestamp, which create the error.
You need to modify the following line (in my script line 478) in the Spotify script:
def updateConnectionDateTime(self):
self.oh.sendCommand('spotify_lastConnectionDateTime',time.strftime("%Y-%m-%dT%H:%M:%S.000+0000",time.gmtime(time.time())))
notice the .000 after %S.