Oh dear, poor Zonya! She certainly isn't post-op trans, so I'm not surprised she was a bit flummoxed by your question. It can't be good for a girl's self-esteem to be asked - especially as you'd barely exchanged pleasantries - whether she used to be a bloke. I suppose they have to have a thick skin, though, in their line of work.
I do agree she's got big feet, though. I didn't think much of it, because she's a tall girl, and with a body like hers, if she had small feet, she'd be forever keeling over. But if big feet are a major turn off, I guess you were wise to walk. Pity, though, because above the ankle she has a fabulous body, and not only is she a really nice girl, I can't remember ever seeing one so eager to please.