No, it is NOT one's duty to inform you that you are factually wrong. In our world, currently, admitting that one is transsexual can be dangerous. Look at you, Henrin. You have said, FOR YEARS, that you would hurt or kill someone if you found out they were transsexual. Transsexuals are often discriminated against and treated badly or differently because of their situation. It is NOT their duty to inform you upon first meeting you. It IS something that they should do IF something might develop. It is entirely possible that when first meeting you, the individual automatically thinks, "hmmm... I have no intention of seeing THIS guy, again". No reason to tell you at that point and risk some sort of harm.
My suggestion would be that, from now on, whenever you meet ANYONE for the first time, the first thing you should do is say, "hi, my name is Henrin. Are you transsexual?" Problem solved.