It's really common. A lot of generally straight women here have written about feeling attracted to their female T's.

I'm more often attracted to women in general and was extremely disturbed by my attraction to my first T. I was young and had yet to acknowledge or accept my sexuality plus being attracted to a maternal figure felt incredibly uncomfortable. I have been intensely attracted to many subsequent maternal transference figures and sometimes felt disturbed by it while other times okay with it.

In general, I tend not to be strongly attracted to women whom I perceive to be straight and this was pivotal in my decision to work with my current T. Within the first few sessions I felt her to be smart, astute, gentle, soft-spoken, unassuming, nonjudgmental, not homophobic... and heterosexual AF. We are reasonably close in age (she's 10-12y older than me) plus she's blond/thin/calm and my thought was that I would not develop feelings of maternal longing toward her. That would have been a real coup but apparently that could not be avoided. Alas. Painful maternal attachments are my Achilles heel apparently.

This to say, having had the bewildering and deeply uncomfortable experience of feeling attracted to a T in the past, I went to great lengths to avoid it this time. So I get how uncomfortable it is and I get the weirdness of having sexual feelings for someone for whom you wouldn't ordinarily have them. Maybe it helps to know 1) it's really common 2) lots of people think that kind of sexual fluidity is a superpower?