I also had a lot of experiences being addressed as female/mam/miss...
1. Back in early 2000, I had to have a sinus surgery. While filling my information and making the ID bracelet, the nurse put an F on the gender marker (even as I was sitting directly face to face). I wasn't even thinking of transitioning back then but gladly take that compliment :-) they corrected it 1hr before the actual surgery, but I've had the ID for more than 10hrs = win.
2. Due to my natural voice which is high pitched, and my androgynous name...I've been addressed as mam numerous time when I'm on the phone. Also taking it as compliment with a smile.
3. A few months ago, I was at the pub with some friends and won a tshirt from a beer rep, but she said "this is a man's shirt, let me get u a girls one" can't stop grinning... loved it.
4. A few weeks ago while looking for some lip balm at walmart, the clerk was asking me from the back "can I help you mam..?" she was quickly corrected herself when I turned around "...err ...sir" but never mind...I scored again.
5. Last week, I had a dinner date with my transgender friend, I told her where I was sitting, what I wore... but she failed to notice me because she thought a girl was sitting there...hehe.. and I didn't wear any female clothing outside, just a hoodie..
This is all pre HRT, and yes I grew my hair a bit longer since 3 months ago, can't wait till I actually start my HRT.