Seriously though, it's a problem. Idk what's wrong with me, I feel the same respect towards someone who is trans as I do anyone else.
With most people I meet, it's because they're speaking too quickly, or without thought. Not that you are being thoughtless, just that you are going through the quickest possible brain pathways to get what you want to say out as fast as possible. One strat I've suggested to people that has been generally successful is to take 2 seconds and prepare yourself - "I know i'm going to be referring to this person. their new pronoun is "X", so I'll make sure to use it." - then go on with what you were about to say. A side benefit is it means you give your brain a second for sober second thought for the dumb thing you might have been about to say.