Gender identity, sexual and romantic orientation, gender expression, and gender roles are complex things, and very few of us wear detailed labels describing just how we are and how we identify.
I have had people question my identity, apparently under the assumption that I am a gay male doing this for some reason they couldn't express. I've had 'supportive' people tell me "you look just like a real woman". The thing is, even though they thought that the questions were valid, I personally found them invasive and insulting.
Lesbian women wearing more masculine apparel face the same thing, others effectively challenging their very identity because they are doing something that others find confusing or 'not right', which these women find invasive and insulting.
Please remember that all of us, lesbian, gay, straight, or transgender, are human beings, with human feelings. Please just accept others as they are. We are not entitled to know what's in the pants of others, or their most private selves. Empathy is vital. Please consider how comfortable you would be in receiving questions, comments, or criticism that you want to offer others. Try to put yourselves in their place.