[delta-chat] Delta notification

Hello everybody, sorry about my english, not a native speaker, this is my first message to this list. Recently installed delta chat. At first was a notification that reads: "connected ... waiting for mesages" or something like that, but right now, that notification dissapeared, I think it is important for Android not to close the app in background. It is this behavior normal ? If not, How do I get back the notification ? Thanks in advance.