That isn't that strange. I generally write contemporary in first, fantasy in third.
Well, nowadays I write almost everything in third. It's a voice thing. The voice of first person is totally different, IMO.
Harry Potter couldn't have been written in first person. The Hunger Games couldn't have been in third. It would have been a different story, to me at least.
I have a real thing about POV, though. I always know, without thinking about it, what POV (or POVs) a certain project will be written in.
I always wonder would Twilight be so popular if it wasn't written in first person.
Lisa, good luck!