I had the same reply at sign-up, but just happened to have an iphone I use for testing, so I signed up and just left the account sitting while I waited for an Android app.
I received an automated email from them about 2 months ago asking why I haven't logged in. I replied that I was waiting for an Android app (expecting nothing in return). I got a reply from someone within a day letting me know there would be an Android app early this year. He even responded to my follow-up email.
Just got the email from them today about the new Android app (automated, not from the same guy). At least from this history with them, I assume they'll start getting those re-invites out soon.