I challenged a friend and this message appeared…what it means?
Idk it happens to me also
Either something would have been server related, or you could try a force restart of the app (and possibly the device).
If it continues after a force restart, then the issue is server sided (most likely).
Try the suggestions in this topic:
http://www.hunterislandforum.com/index.php/topic/783-need-help/?hl=inviterejectedmessagekey