I can't believe I forgot to post this earlier.
I just moved to Northern Virginia from Minneapolis, MN. My best friend has a job with Homeland Security in DC and told me that because of me he attempted to get on the team that was developing the training for working with transgender passengers. When I went through screeningI was very happy with how I was treated. I immediately texted my friend this message:
Just got through screening. You can let the people developing training for screening transgender people know that I was treated very well at DCA. I was quietly and respectfully asked if I identified as male or female by the woman at the scanner. I told her female. Then I realized she was referring to the body scanner, so I said "For the purposes of the body scanner, you'll want to mark me as male." After I got through, the guy behind her said "You can step this way s[ir], ma'am."

It was a validating experience. I honestly didn't expect it because I had my hair tied back and I wasn't wearing feminine clothing. Must have been the nails. Haha! My friend hasn't had a chance to tell the training team, but he said he emailed the security director at Reagan International airport and that the security director sent out a memo to all of the screeners letting them know how I felt about my experience.