He called me dude?

My guy friend (who I like but haven't flat out told him that) decided on Friday, on our 16 hour road trip, to call me "dude" every time he talked to me instead of by my name. He called all the other girls by their names. Until Friday, he has ALWAYS called me by my name. WHAT IS UP WITH THAT? We became alot closer on our trip. But, I'm asking, is him calling me dude indicating that he thinks of me as a really close platonic friend, or one of the guys, OR is it showing that he maybe thinks of me as more than a friend???