There's a white thingy (fungus?) on my Phal!

[whitetshirtguy]

Hello, guys...
I hope you're not tired of helping me with my messed up Phal yet.
I have just repotted it a week ago because the media was very decomposed and the roots were rotting. I desribed the repotting here.

I am using a pencil to check if it needs watering, and since I was sticking the pencil to the media kind of often I was afraid of accidentally damaging the roots while doing it, so I decided to just leave the pencil there and only take it of to check how wet it is. Was that a bad idea?

The thing is that when I took the pencil out and checked it yesterday there was a white thing sticking to it. It looked like something between flour, cotton and a spider web. There were little dots of it and little fibers.

I thought it could be some sort of fungus, so I googled "white fungus roots" and found this: Mycorrhiza - Wikipedia, the free encyclopedia
The thing on the pencil kind of looked like that one on the first picture in the article, but a little more dense and not so widespread.
I didn't think of taking a picture of it at the time, and just wiped the pencil clean and put it back to it's place. Now today, when I took it out to check again, there was no white thingy anymore.
The Phal is on a clear plastic pot, so I can see a few of the roots on it's walls, and they seem green and tidy as they always did (no white thing).


So... what is that? Is it bad? What should I do!?

Thanks again for all your help,

W.