I think you've hit the nail on the head with this. I don't understand why people are so interested in labels in general and, in this case, why everyone has to be either 100 percent gay or 100 percent straight.
This usually comes up in the other direction: a male who previously has only had sexual encounters with women has, for whatever reason, some sort of sexual encounter with another man and he wonders if that one encounter means he's gay. My response would be: of course not. Think of the reverse. If someone like me, who's only been with other men, were to have one sexual encounter with a woman, does that mean I'm suddenly straight? No, I'm pretty sure the only thing straight about me is the direction of my dick pointing straight up in the air as some dude pounds the beejebus out of my asshole!
I think Kinsey had it exactly right--while there are maybe a few people who are, in fact, 100 percent gay or 100 percent straight, the reality is that the overwhelming majority of people fall somewhere on the sliding scale. True bisexuality would be 50/50, but people can be 90/10 or 67/33 or whatever.
If you insist on labeling yourself, I think sexual orientation (i.e. am I gay or straight?) is truly about how one is "oriented," as in, I would rather be married to a man than a woman, I would rather have my boyfriend hold my hand in my hospital bed versus a girlfriend, I find more enjoyment hanging out at gay bars, with gay friends, or discussing gay culture, etc. and not so much about discovering one or two physcially attractive women who happen to turn you on.
Because at the end of the day, refujiunderground, who the fuck cares what you call yourself? If you want to have sex with men, have sex with men! If you want to jerk off to pictures of naked women, then jerk off to pictures of naked women! Who you are or what you like or don't like to do isn't anyone's business except yours and your partner's.