The latest version sends a debug log to the server when you post to the iOS forum. I see you have now installed the latest version. But this may have been posted prior to installing it as I do not see the debug log.
Best guess is that resources on your device are low enough to trigger the app to release memory (a normal occurrence) but it's not recovering correctly. The log should throw some light as to what state it is trying to recover from.
If you could make it do it again and post an image that would be really helpful.