I'm a sexist asshole and I didn't even know it until yesterday

At least the guest knows that it's wrong to think like that

But women make better surgeons as they tend to have smaller hands and fingers, and greater dexterity. Better that then a pair of huge hairy man-hands poking your insides around?
;)

My dad's a really good surgeon and even he said that at the hospital there were some female surgeons that were a trillion times better than him

It's implicit bias, you don't mean to. And it's good you noticed.

I want to be a female surgeon.... I hope that feeling isn't universal

Depending on the surgery, the guy could just be subconsciously more nervous about the fact that a woman is going to see his body (Not in a "I'm a virgin, no woman's ever looked at my body" way, but in a more general "I'm fine if a guy happens to see me nude in the locker room, but would freak out if a girl saw" could also easily reverse the sexes too, lots of women feel more comfortable with a female OB/GYN)
Or I could just be over thinking it and the guy is just a sexist that is nervous a woman will botch the surgery.