Twice now I've gotten an Exotic Helmet after completing the VOG Raid. The first time it happened, an exotic Engram dropped from the Relic Cache itself. I picked it up and it turned out to be an exotic helmet instead of Vex. Thought it was a glitch, so I shrugged it off. I didn't capture a video of it at the time. This time though, after beating Atheon, I got another exotic helmet. Video included. Not sure if this is a bug or not, but reporting it nonetheless.