^ Yep. I've been stealth through a (non-invasive) physical, where a nurse palpated my organs and listened to my heart, and this was even when I still had to wear a binder. It was a pre-requisite for donating plasma. I'm at the donation center a lot, surrounded by nurses and phlebotomists and all manner of "professionals." My ID said male and that's how they put me down. I've been going for exactly a year, and one year ago I looked way different than I do now, but it hasn't registered as weird with anyone. At the core of it, people are just people and if you say you're male and you at least vaguely look and sound like it and you're confident in your gender, it's not going to blip anyone's radar.
Also was recently at the ER after splashing oil on my eyes. Sometimes they'll pull your health records up when you check in, and it'll have your birth sex on there if you haven't changed it yet. But they didn't do that at this hospital. I just briefly explained why I was there and they printed me off a bracelet with an M. So even at a hospital, around trained professionals, nobody questioned that I was male.
