I remember Polar Bear vol. 1 said something along the lines of; "Never show her your weaknesses, or she will use it against you!" LOL
Anyway, I'm glad you told her about your transplant actually, as it can only be used against you if you let it.
It might have scared her away if you told your whole premature baldness - panic attacks - psychiatry - transplant saga while sobbing uncontrollably on her shoulder, but casually discussing it can be healthy for your relationship and bring you closer.
Personally I will keep the worst of my hair loss anguish to myself, my therapist and this forum, but if the guy I'm dating asks me questions about it I will of course answer them, still without going too deep into my story, though.