My typing error turned out to be an actual command in vim. How to undo?

I use VIM 7.3 with included patches 1-55. I don't know exactly what that means, but that is what the screen says .

I typed something incorrectly. It turns out what ever I did was the correct command to highlight the word "if" every time I type it ( as part of an if condition).

How do I undo this?
Thanks