Southern Comfort: Pronouns and Transsexuals

As someone who is no stranger to the LGBT community, I nonetheless have had minimal exposure to transsexuals.  What this movie impressed upon me the most was that when I went to talk about the film to my friends I was getting my pronouns all mixed up as I talked about the characters.  I was using both he and she or his and her in the same sentence talking about the same person.  I realize if I had just seen these characters in the movie without knowing that they had sexual reassignment surgery, I would have had no problem using the proper pronoun (the pronoun they would have everyone use); however, throwing this knowledge into the mix makes it complicated and I rightfully do not understand why.  It is almost as if we are socially ill-equipped to talk about these individuals with an understanding of who they used to be.  That's incredibly paradoxical, however, because they would want us to identify them as they are now without regarding who they once were, and I believe we feel the urge to do just the opposite.  I think that's an interesting problem and probably says more about us than I can divine at this moment.