In my experience, dreams rarely literally mean what we consciously think they mean. It strikes me that the first sentence in your post seems like it could be relevant.
The brain uses association and relation with its imagery. I'm not sure your original organ was meant to mean your actual organ. But what it represented. Not in a physical sense, perhaps. Maybe your brain was just using that to represent your resurgence in the ability to orgasm, and maybe the feelings you have about that, using the only frame of reference it had. I'm not so sure it was to do with your relief that it was still there, in a literal sense.
I dunno, dreams are funny things. One time I dreamed I was a horse. I have no idea how. But in that dream it felt very real. I have no idea how I knew it felt real, it just did.
Sometimes... thank heaven we wake up, lol.