I started a second warlock, and was doing one of the venus misions (i think it was the one where you go to the old overgrown research site). Anyways, I passed by the VOG entrance, and the spire was forming. I thought "cool, someone is doing the VOG," but there was NO ONE there, i rode over to one of the sync plates and was one-shotted by a hobgoblin.

Has anyone ever noticed this before? Maybe during your first campaign play-through it forms to draw your attention to it? After i re-spawned, I hung around a bit and watched the whole spire form, but the door never opened, and there was no one around except my friend and I.

I was a level 11, and he was a 14.

Yeah, I've seen the spire start and finish building by itself, while no one else was around. Door didn't open, though.

I entered the VoG after a group opened it. I got stuck and had to goto orbit :)