Posting this here, as this can not be intentional.

One benefit of the orange eye effect of the vampires is that it shows us clearly who is and who isn't a vampire. When playing my vampire character, who dwells in solitude, I feed on the castle mage as she seems to sleep a lot and is very easy to get to.

I went in to feed after installing Dawnguard and found myself merely pick-pocketing. I wondered whether the mod had somehow reset vampires, so I checked.. nope still there. I simply try to talk to my intended victim and she wakes up and looks at me, with a nice pair of glowing orange eyes.

Has anyone else noticed NPCs they have previously fed on turning into vampires?

If this is intentional it is an enormous mistake - if you change NPCs into vamps by feeding on them you'll run out of people eventually and the whole "I am a vampire" thing will lose its appeal anyway if you make everyone in Skyrim a vampire.

That NPC has ALLWAYS been a vampire xD Its just more noticable now, and i guess they changed it so you cant feed on vampires.