Hi Andy,
I don't know what this thing was, but I just think it's neat that you're getting experiences.
I agree with Recoverer that you can't be sure what it was, and the "dark mass" aspect concerns me a little.
But what I notice is that you said you felt great, and that's a great sign I think. You said you haven't needed confirmation for a long time now, and I think the reason you're getting more experiences is simply because you haven't been in a "need" mode. I notice that at the times I feel I am needy the most, that's when I don't get anything. Ironic isn't it? But you know what they say, you have to "let go" and things will happen when you least expect it.
Also, I know from my own experiences that sometimes I think I'm literally wide awake physically only to find out that I actually wasn't. Some OBE states are like that, and especially what I call the lower ones where perception can be a bit frightening, like having the feeling of being paralyzed. But again, you were feeling great and happy, not scared, and I think it's important to solidly know what you're feeling and always trust that first and foremost. Anyway, if you're sure that you were physically awake, you're perception and openness to these kinds of experiences seems to be growing.
Whatever this experience was, it doesn't seem harmful or negative. And i'm assuming you'll be having more soon because your perception to this kind of stuff is very open right now.
Great! Can't wait to hear more.