I knew I was seeing ghosts…so I caught one on camera. I often noticed that when I was replying to emails on my Windows Phone I was getting a faint ghosting of the keyboard in the email. Take a look at the photos (the second one I played with the contrast a drop to help you see it). The letters “BNM ‘delete’ and V” are all noticeable and above that you can see the attachment icon in the subject line. If you have a Windows Phone test it out for yourself. I’ve looked at it a bit and the easiest way to see it is to reply to an email that has a few replies in the chain (even if conversation mode is off) and it’s best if the subject line is one line. And thar she blows. Weird right? You can get it if you move the cursor around on other emails as well though and it’s faint generally but sometimes it’s more noticeable than others.
Confirm that you’re seeing what I’m seeing in the comments but I recall seeing this on my phones since the early days of WP (from my Focus to my Titan and now my Lumia).