Minor rant: I requested an invite and got one but they didn't have an Android app and thus wouldn't let me sign up. They were supposed to send out another invite once the Android app was available. I'm probably just being impatient but I am actually really interested in trying their service.
I'm guessing that you'll get one soon. That's not necessarily blind faith, as my communication with them so far has been impressive.
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.