slip of the pen

Others suspect the change may have come from a slip of the pen.

Others suspect the change may have come from a slip of the pen.

Others suspect the change may have come from a slip of the pen.

Others suspect the change may have come from a slip of the pen.

I’ve seen UK Uncut make this mistake on Twitter before now so it’s not just a slip of the pen or a sudden seizure or brain spasm.