seen is a word isn't it?

I know a person who, for some reason, doesn't use the word "seen".

 

For example, "Have you seen Mike?" is "Have you saw Mike?".  Seriously - I've known this new person for about 10 months, and haven't heard the word "seen" ONE TIME.  And I've been listening for it, because it makes my ears hurt when I hear "Have you saw the book?".