Yikes, that could have ended badly!
I’m not aware of any time limitations for the irons – I have left my irons plugged in for much longer than two hours without any sign of problems, and I haven’t heard of anyone else having this problem either, so I think maybe you were unlucky and received a bad iron. It’s unfortunate that it takes so long to get a new one… I hope someone will see your note and help you out!