My guess was that they did it quickly before and used the Google or iTunes payment thing. Now they want your contact details and to control the subscription themselves. Is that plausible? The app knew you had subscribed already?
I checked and I had paid via iTunes.
I did wonder if this meant I could now log on via the web rather than the app and have the access there too. I haven't checked.
(Sorry for the painful autocorrect in my last post. I'd before? I ink?
)