Since the beginning of July there has been a slight change to the display when you touch in or out. I’m still trying to get full details, but this is what I’ve worked out so far. Whenever you touch in and your balance is below the maximum journey charge the system will display a “Low Balance” warning message. This also happens on touch out. There appears to be account taken of whether you have already capped or are close to doing so, certainly on touch in but possibly also on touch out. If you have auto top-up enabled then it is unlikely that you will see this warning as the top-up will happen before it decides whether to display it.
This isn’t all good news though.