I had a similar experience today. I was getting blood drawn for my six-month checkup. Though I was presenting as Kathy, all my ID, in particular my health card, are all still in my old name. At each step of the process (check-in, entry to lab, greeted by the nurse), they confirm your identity. So I was repeatedly dead-named at each step.
I figured that there is no point in confusing the paper pushers, since I want my lab work processed properly and sent to the right doctor, so I reluctantly went along with it. "Well, officially, my name is still ... " It sure grated on my nerves, though.