He called me DUDE?

I sat w/ my guy friend (who I like) most of our 16 hour road trip today.He wouldn't talk to me as much as he usually does.He would look me in the eye and poke me occasionally (or clap in my face) as a joke, like he does with all the girls.But, he every time he talked to me he called me "DUDE".He calls all the other girls by their names.What's w/ that? On monday he told me Mi Amor and claimed it means "you're special".Now he claims he doesn't remember what he said on Monday.On Tuesday night he tried to play my favorite song on his guitar when I asked him too, even though he’s only heard a little audio clip of it and was going by ear. But,he suddenly on the trip wouldn't invite me anywhere (like to the beach or anything.) He told me last night "cause you'll come whether we invite you or not." He also was a jerk at dinner and wouldn't look at me or talk to me AT ALL.But an hour afterwards he was acting like everything was cool again?This DUDE thing is new.Before today he has ALWAYS called me by my first name.Yesterday morning we had a huge, very personal conversation that is confidential and he asked my opinions and advice.Then today, he wanted me (AND ONLY ME) to read a very personal letter he wrote.