I went all the way through the Dawnguard main quest and got to the conversation about not being a vampire anymore. She said she would submit to the process and left. Well just yesterday I went to the Dawnguard castle to check to see if she was back and she was. I noticed that her eyes were still yellow and glowed but didn't think anything of it. After she followed me for a while I noticed she had her hood on outdoors, which was weird "not" being a vampire anymore. Then in combat she still rasies the dead, and svck life out of enemies. So is she just broken or has this happened to you?