I was distressed about something else when I did that - so - not thinking about the task at hand!
It's not a major disaster - although the carpet is crispy there. I was standing nearby and smelled something "funny".
The bottom of the iron is shiny - so the gunk ironed off on brown paper bags. What did not come off right away, I used Scour Off by Shaklee to remove. (I could not find my iron cleaner stuff.)