Unexpected Change to .vimrc

[funknut]

Not a bug as much as a support request, although it's possible there's a bug. I had a single line, containing only ":x", appear in my janus created .vimrc. I did edit the file at one point, but only because I was unaware of the .vimrc.local at the time, and only to add a color scheme. I since corrected the issue, and used vim without issue for a few hours, then suddenly, the ":x" appeared in line 30, just after the line disabling plugins, and just before the line where pathogen is loaded.

Is there any reason this could have happened aside from my own error or negligence?