I'm pansexual, but i still believe our preferences and attractions can slide around on the continuum that sexual preference is. As much as we human and our cultures like to paint it as a binary two position switch or a three position switch where bisexuality is "neutral". I think that fails most people.
Sometimes i think we get aversions etc from deeply buried biases that we learned as a kid. Lately women sort of seem non-attractive to me and men very much more, but i will still say that it it more based on the individual than the category as a whole. Having said that, i can say that other than a bit of facial scruff or hair, kissing a man is very similar to kissing a woman.
In general my sexual attraction is highly dependent on the emotional connection and that was never the case before. I can look at beautiful men and women now and appreciate their features, bodies, skin, hair, the way they dress, etc. but its hard for me to imagine anything intimate with them because i don't know them.
Accepting that these things can change a bit is in my opinion, healthy. Personal preference, turn ons, fantasies etc are all part of what makes us unique. I think you saw a nice looking guy and appreciated that visually and that is completely the norm for many of us.
