It seems that Mountain Lion now has taken over Lion in the App Store everywhere, Lion isn't even in the purchases list anymore. I assumed that since ML is a new 'app' and not a free update, it would simply appear in the list of purchases alongside Lion, but this is not the case. In case I need to re-download 10.7.4 for testing purposes, I can't even access my legally purchased software! That is just ridiculous. So, if anyone reading this needs to reinstall Lion in the future, download and save the installer now, before purchasing ML.