Spider(?) web around roots in container.

Hi all,
Sorry for the lack of image, I've already repotted the plant now and didn't have a clean hand/camera.

We've got a Pinus densiflora "Haybud"/"Heavybud" and when I pulled it out of it's current container, I could see the entire compost 'puck' was coated in what looks like a spiders web.  It feels like spiders web, and there is a little of it under the pot and on bricks below the pot.
It's odd, one expects to see roots slightly wrapping around the compost puck (yes, they were) but it's odd seeing a white carpet over the entire thing.  None on the top of the compost though.

I have seen it, to a lesser extent on some other plants around the area.  It was just quite a sight on this one that I considered posting to here.

I have scraped as much of it off as I could and discarded it.

As we've a fair amount of gravel, and I've seen little spiders running around in it and under paving slabs that I've placed around, I am assuming it's just those and not really any cause for alarm.  Perhaps, as it's a pine and I'm more reluctant to make it too damp, the drier compost and perhaps slight shrinking from the pot edge gave itself as a nice place for (harmless - hopefully) spiders to hang out.

Thanks for any input.