That's what I thought, but I've been seeing it more and more. I guess spellcheckers are to blame -- they don't spot this, and people don't bother proof-reading what they type anymore.

And so more people read it, and assimilate it, and so, whether consciously or not, start using it in their own writing -- this being how language always evolves. Look at the whole "medieval" versus "medireview" story.

Peter