Collapsed rock even if small clearing area

[SplintDK]

Greetings,

I just played the game, and I found some metal ore that I wanted to mine and clear away to store it and use it. So I find this small rock, and I decide I wanted to remove it completely.

So this is what happened, I cleared it all, but even though it were all gone, I had a collapse in the building.
http://prntscr.com/5mqfpa

Not sure if it's a bug, but, now it's reported.

Best Regards,
Splint

[Geertje123]

Do a 'no roof zone' over it, and then remove that zone again.

If that doesnt work it might be a thick mountain roof (and not the thin one on the edges) which you can't remove