Cannot say whether it's discharging as quickly as it would be without being connected, but yes, my impression is that in both cases (both the "not charging" state and, like this time, "discharging"), the phone is actually discharging. I'll have a closer look, though, as I'm also running the AccuBattery app which should be able to authoritatively answer that question.
[Edit:] Yesterday:
06:52: used for 32m, 75% -> 70% (this was the normal discharge cycle. After that, charging should have started again)
07:24: used for 7h 38m, 71% -> 28% (connected all the time; at 28%, st