Totally normal. First off - don't worry about labels. Don't pigeon hole yourself into gay or straight or bi. Instead - do what you feel right and what feels good to you. If guys turn you on and you enjoy being with them - awesome. If you think about girls, wonder what it would be like with them and the opportunity presents itself one day - give it a try. The worst that would happen is that you'll decide you don't like it. Which is totally cool too.
It is very possible that while you might fantasize about being with a woman, if the opportunity presented itself to you, you might think twice. I have fantazied about threesomes or doing things sexually that seem exciting - but i'm pretty sure that if I was ever in a position to try them i'd just chicken out. But its nice to think about them and get excited about them.
Ultimately - don't stress over whether wondering about what its like to be with another woman or dreaming about being with another woman or finding another woman attractive is more than it really is: a fantasy, a dream or enjoying seeing someone woman. If this is something you really want to pursue - give it a try. If not, just enjoy your private thoughts. Nothing wrong with either one