This was not the noise of the nagual, in any way for us - it was for Carlos because Genaro was playing tricks on him. Genaro was attracting his 2nd Att, and that meant, from the AP position CC was lodged in, the nagual. But that does not mean the nagual makes creepy noises. Anything that approaches us from the 2nd Att, due to our AP position predominantly oriented in the 1st Att, is going to be the whispering of the nagual. This is based on the fairly essential and simplistic breakdown of existence into tonal and nagual (which I don't disagree with).
But no one should begin to associate the nagual with spooky things. Genaro was pushing Carlos very hard, and Carlos had his own addiction to spooky, so put the two together and there's the story. It is natural for the whisperings of the nagual to have a very unsettling effect on us, due to the fact we have concocted a world in which this element is denied. But that unsettling, even profoundly disturbing or fear, is not necessarily creepy-crawly unless you are doing that kind of ceremony.
So to your story, that is correct for you at that time (this is personal), that something, whatever it might be, triggered your nagual side. It matters what it is from the point of us trying to negotiate the 2nd Att, but doesn't matter from the point of us trying to crack the tyranny of the tonal.
The reason I always try to drag people away from any obsession with spooks, is because Carlos did us a serious dis-service by his own obsession with the dark and heavy side of the nagual. This has left a dank stink around the whole toltec scene sponsored by Carlos. You find it in forums based on Carlos's works, and quite frankly I find it childish. The nagual is filled with the most fantastic and wonderful, so to get trapped in the dank heavy side is very unfortunate.
Of course there is fear - worse, I'd easily use the word terror. The things we have to do can bring us through the most disturbing things imaginable, but these are just corners of the 2nd Att that we pass through. It is of paramount importance we do not allow such corners to colour our entire journey through the 2nd Att. There is also ecstasy and beauty, but more significant, is the empty. Oddly we seem to have to spend a lifetime before we discover the empty.
The Guardian is closely connected, and alas, this is really what we are speaking of. What stands between us and the nagual is accumulated rejected feelings of a lifetime. So we have to pass through a veil of our own unexamined emotions before we are allowed any kind of freedom. This is why it is best to begin the task of depleting that accumulation before we do too much nagual work.
Your fear is a combination of the terror of your tonal discovering it's not the only world, and your Guardian. Every time you connect to the 2nd Att in this kind of way, the fear will lessen. You'll still feel the thrill of the nagual, but fear will be replaced by excitement. It just takes time and experience. On our path, we walk the liminal - always.