It's a good thing you noticed the wrong pen after your morning jab. Things could have got quite sticky.Looks like I have cracked it! Levels are starting to drift upwards (8.9 at the moment) which will probably be that 4unit Levemir deficit starting to have effect. Need to get out and get some exercise now as don't want to inject any more Fiasp just yet.
It sounds like you did everything right after that. A first class save.