A. She probably wasn’t paying much attention to the height. She probably just glanced at it to make sure you’re an average height.
B. Maybe she was very tired or had another reason for not wearing heels (something with her foot)
C. I really, really hope you’re kidding.
D. If this is the only issue you can find, you’re obviously dating a very special person.
I’ll add that I’m single and I don’t own a pair of heels. I think they’re bordering on not tznius (but thats just me) aside from being incredibly uncomfortable (not just me).